Oooh…lovely question.

Spoiler alert: Going to be a very long answer. I'm going to mention the moments that happened in books which were changed or ignored in the movies. Would suggest the new fellas first read or watch the Harry Potter series for better understanding and to avoid spoilers.

So let's start from book 1.

Philosopher's Stone

1. Harry had dreams of some flashing green light and even a flying motorbike. Dudley's friend Piers also joined the Dursleys at the zoo.
2. Vernon took the Family to a Hotel named Railview to escape the continuous letters from Hogwarts.
3. Dudley always roamed around with his Smeltings Stick banging here and there.
4. Hagrid stayed with Harry on his birthday night with him in that shabby place, waking up the next morning to take him to the Diagon Alley.
5. Hagrid was there with Harry at the Ollivander's where Ollivander also greeted him asking about his wand which was snapped in pieces. But actually, it was hidden in Hagrid's umbrella.
6. Harry met Draco for the first time at Madam Malkin's robe shop where he was about to tell Draco his name before the owner of the shop interrupted them.
7. Harry named his Owl Hedwig after reading this name from the book History of Magic.
8. Hagrid never took Harry to the King's cross. He just gave him the train ticket as Harry had one more month to spend at the Dursleys before attending Hogwarts. Dursleys were the ones to accompany Harry to the King's Cross station on Sept. 1st.
9. Fred and George were the first ones to find out the real identity of the skinny boy Harry Potter. Molly warned them not to talk to Harry about his parents or the dark lord.
10. Hermione mentioned to Harry on the train that she read about Harry before in some of the magic books.
11. Malfoy's next meeting with Harry is on the train where he offers Harry to befriend him and Harry rejects.
12. Neville's toad was found by Hagrid near the black lake before entering the school premises.
13. The sorting hat sings a song before the sorting ceremony and this song changes every year.
14. The names of the students for the Sorting Ceremony are called by the Alphabetical order of their surnames.
15. Peeves was never mentioned in the movies. He was a poltergeist and always created chaos at the school.
16. Harry attends the Charms class first in the books.
17. Harry and Malfoy arranged a midnight duel.
18. Harry and Malfoy arranged a competition of duel at midnight which Hermione found out. Hermione tries to stop Ron and Harry from going there and accidentally gets locked outside the common room when The Fat Lady goes somewhere. They encountered Neville near the stairs who was sitting outside as he forgot the password. When the 4 of them realized that it was a trap and they were about to get caught by Filch, they accidentally went to the room where Fluffy was hidden.
19. Hermione used to conjure blue flames in a jar to keep the three of them warm during winter.
20. Snape refereed the 2nd match of Quidditch to ensure the safety of Harry after the happenings of the first match.
21. Harry visited the mirror of Erised 2-3 nights in a row.
22. Harry received a fifty-pence piece from Uncle Vernon as a Christmas present. Molly sent him some sweets and a Jumper as presents.
23. Fred and George threw Snowballs at Quirrell's back of the turban.
24. Ron got bitten by Norbert on his finger due to which he had to stay in the hospital wing.
25. Harry and Hermione took Norbert to the tallest tower where Charlie Wesley's friends took the dragon with them.
26. Malfoy was trying to report them to McGonagall and Neville was stopping him, resulting in the detention of Neville himself with Draco, Harry and Hermione when McGonagall caught them near the tower. Ron was not with them as his injured finger led him to the hospital wing.
27. Except for Firenze, Bane the centaur was also introduced in the book who started working as a professor in Hogwarts.
28. Harry had to use his flute to get Fluffy to sleep as the harp was not playing itself.
29. Harry and Hermione had to get through the Potions quiz by Snape after the giant chess. This means the security measures for the sorcerer's stone were kept by almost all the main professors of Hogwarts. Flying by madam hooch, charming the keys to fly by Flitwick, Live Giant chess transfiguration by McGonagall, Potions quiz by Snape, Devil Snare by Sprout and Fluffy by Hagrid.
30. Quirrell's body was left burnt on the floor. In the movies, he was converted into dust.
31. Before Harry knew about his wizarding identity, he used to show some indications of magic inside him unintentionally. Aunt Petunia used to cut down his messy hair short only to leave a bit to cover his scar but Harry's hair grew to its usual mess the very next day. He even unknowingly appeared on his school's rooftop once while being chased by Dudley and his gang.

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Chamber of secrets

1. Harry used to frighten the Dursleys with wands, especially Dudley. He enjoyed this a lot. He hid the fact that he was not allowed to use magic outside the school.
2. Dobby threw Petunia's pudding down on the floor and not on the guest's head.
3. Usually, house elves make cracking noises while vanishing or appearing suddenly.
4. Harry received an owl with a warning from the ministry not to use underage magic again out of the school as they found out that a hover charm was used at the Dursleys. Which resulted in Uncle Dursley fuming up as Harry used to fright them with wands sometimes.
5. There was a ghoul in the attic of the Burrow who howled whenever he felt it was too quiet.
6. When Harry accidentally turned up in Knockturn Alley and saw Lucius and Draco Malfoy, he hid in a cupboard in Borgin and Burkes where the father and son turned up.
7. Arthur Weasley (not Hermione) helped Harry to clear and repair his glasses when Harry reached Diagon Alley with Hagrid.
8. (In the first two films, Hermione shows no fear of the name Voldemort, speaking it without difficulty in the first film). In the books, Hermione never uses the name Voldemort until the fifth novel, and even then it requires courage. The films have a bit of a continuity issue on this point as the fifth film shows her getting the courage to say "Voldemort".
9. Harry and Ron had peacefully driven the car until they reached Hogwarts. They never were chased by the Hogwarts Express nor Harry was not thrown outside the car, hanging in the air.
10. After Snape scolded them, McGonagall came to them ALONE and asked them to have dinner in the office only.
11. Neville was good at Herbology. He NEVER fainted in the Herbology class due to Mandrake's cry.
12. In their first DADA class with Lockhart, he gave them all a paper for a small test which included only the questions about himself like what is his favourite colour, or his greatest achievement.
13. Hermione never knew the meaning of Mudblood. Hagrid told them the meaning of the ill word.
14. The trio were coming back from the Deathday Party of Nearly Headless Nick when they encountered the petrified body of Mrs Norris and the Message of the Chamber of Secrets.
15. Dumbledore examined Mrs. Norris closely in Lockhart's office before declaring her petrified and not dead.
16. In the whole book, Ginny seems to be terrified, upset, nervous or lost in thoughts, sitting alone and not talking to anyone much. The movies ignored her completely.
17. Professor Binns, the History of Magic Professor was the one to tell the students about the Chamber of Secrets. He was the only GHOST professor in Hogwarts.
18. Myrtle has been upset with Hermione since the Deathday party.
19. Percy scolds and deducts points from Griffindor after watching Ron and Harry roaming near Moaning Myrtle’s bathroom.
20. George successfully tried and put the rogue bludger in the box. Hermione never blasted the bludger.
21. In the duelling club, Hermione too duelled with Millicent Bulstrode, it was then she collected a hair sample of Millicent (or she thought so) for the polyjuice potion.
22. Harry saw the sorting hat in Dumbledore's office and tried to put it on his head to ensure that he belonged to Griffindor. And sorting hat again said that Harry would have done well in Slytherin.
23. Ron was the one to point out that hearing voices even in the wizarding world isn't a good sign.
24. Fred and George had fun terrifying students with the name of Harry being the heir of Slytherin.
25. Dursley's sent Harry a toothpick as a Christmas present.
26. Ron and Harry hid Crabbe and Goyle in the cupboard across a room. And took off their clothes and shoes for themselves for the aftermath changes of the Polyjuice potion.
27. Lockhart sent a well wishes greeting to Hermione when she was in the Hospital wing due to the wrong polyjuice potion consumption.
28. Lockhart sent card-carrying cupids roaming around the school the whole day on Valentine’s Day delivering students their valentines when they carried a message for Harry. It was then when Malfoy tried to tease Harry and somehow Harry's bag fell and the Riddles' dairy got soaked in ink. Harry aftermath realized that the diary was not covered with ink.
29. The students were given lists to choose the subjects as options for their next year although DADA, Transfiguration, Herbology, Potions and Charms were compulsory.
30. Dumbledore told Harry and Ron would be receiving special awards for Services to the school after they helped Ginny out of the chamber alive.
31. Lockhart lost all his memories for a lifetime and was sent to St. Mungo's for treatment.
32. Lucius never tried to use the killing curse on Harry. The killing curse was introduced in the fourth book.
33. Percy had a girlfriend named Penelope Clearwater.
34. Harry gave Dursley's telephone number to Hermione and Ron to call him during the summer holidays.
35. The Weasleys (Molly and Arthur) visited Hogwarts after they got the news about Ginny being dragged into the Chamber of Secrets by the Heir of Slytherin. When Harry, Ron, Ginny and Lockhart reached Dumbledore right after getting out of the chamber, they encountered Ginny and Ron's parents there. Molly and Arthur even thanked Harry a lot for saving Ginny's life.

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Prisoner of Azkaban

1. Harry was not allowed to use a wand outside the school. He used his torch to study or complete his homework at midnight.
2. Aunt Marge gives her dog Ripper Brandy to drink and not tea.
3. Harry had dinner with Dursleys and Aunt Marge before the insulting conversation about his parents. He bears the taunts of Marge for days in a row as he makes a deal with his Uncle Vernon that if he behaves in front of Marge and is silent about Hogwarts, then Uncle Vernon will sign his permission form from Hogsmeade. But Harry loses his control on the last night with his aunt and blows her up.
4. Harry pretends to be Neville Longbottom in the knight bus.
5. Harry asks Cornelius Fudge to sign his Hogsmeade permission slip but he refuses.
6. Harry had 2 weeks after reaching the leaky cauldron to start his next Hogwarts term, so he stayed at the leaky Cauldron for the time being.
7. Harry was there with Ron and Hermione while Hermione was buying a cat for herself and Ron was buying medicine for his rat Scabbers. They did their Hogwarts term shopping together, except Harry just accompanied them coz he already bought his books earlier.
8. McGonagall asked Harry and Hermione for a talk before the feast. She talks to Harry with Hermione but takes Hermione for a lonely personal talk where she gives Hermione the time turner due to her schedule.
9. In their first care of magical creatures class, the Slytherins and Griffindors meet not only Buckbeak but a herd of Hippogriffs for their lessons.
10. In the book, Buckbeak and Harry fly only once around the paddock in the Forbidden Forest. And Harry doesn't quite enjoy the ride.
11. Malfoy bleeds after Buckbeak attacks him. He was successful in stroking the Buckbeak first but then he insulted it resulting in his injury.
12. Parvati's boggart is a Mummy and not a snake.
13. Peeves was the one to tell Dumbledore that Sirius black attacked the Fat Lady.
14. Harry spends his Hogsmeade weekend day with Lupin in his office seeing the Grindylow which Lupin was taking delivery of for their next lesson.
15. Sir Cadogan's portrait replaces Fat Lady's portrait outside the Gryffindor common room. Which led the Gryffindors to be annoyed a lot as he was a bit crazy.
16. No one was able to see properly the match of Quidditch with Hufflepuffs. Hermione casts an impervius spell on Harry's glasses making him easily see the snitch.
17. In the book, Harry falls off the broom and Cedric catches the snitch. Cedric Diggory was introduced in the 3rd book as the seeker of Hufflepuff.
18. In the film origins of the Marauders were omitted. The Shrieking Shack was placed at Hogwarts for Remus Lupin as he turned into a Werewolf every full moon and lost his control. Dumbledore planted and created the Shrieking Shack for Lupin to spend his transformation nights in there. The other three friends of Lupin- James, Peter and Sirius got to know about Lupin's secret in their third year and the three of them decided to transform into animaguses to spend the full moon nights with Lupin in the Shrieking Shack accompanying him.
19. Harry was with Hermione and Ron at the three broomsticks when he heard the conversation of Fudge, McGonagall, Hagrid, Flitwick and Rosmerta about Sirius and James's friendship and Sirius's betrayal. He was hiding under the table. He went to Hogwarts alone after that and Ron and Hermione joined him after a while.
20. Harry receives his firebolt with no note in it eventually which is revealed that it was Sirius who sent it to him. Hermione makes sure that McGonagall confiscates the firebolt to check if it is dangerous and Harry gets his broom back after weeks of examination of the Firebolt by McGonagall and Flitwick.
21. Harry fails many times before conjuring a non-corporeal patronus in Lupin's office.
22. In the books, Ron was the one to stand in front of Sirius saying, “If u wanna kill Harry you have to kill us first". He was never as dumb as he was shown in the movies.
23. Cho Chang is introduced in this third book as Ravenclaw's beautiful seeker.
24. Harry throws mud balls at Malfoy during the Hogsmeade trip, kicks Crabbe and pulls Pike's cap on his eyes.
25. When Snape tries to open the Marauder's map, each marauder insults him differently.
26. Hermione slaps Malfoy on his face.
27. Hermione becomes too tired eventually in the books due to her class loads that sometimes she even sleeps forgetting to take her classes.
28. Harry witnessed Trelawney entering the trance while he went to her room for his final Divination practicals.
29. In the book, while the trio are on their way to Hagrid's hut during Buckbeak's execution, they bring Harry's Invisibility Cloak with them.
30. In the novel, during the trio's visit to Hagrid, they follow him out to his back garden where he comforts Buckbeak and says "It's okay, Beaky."
31. Crookshanks never recognises Sirius as an Animagus in the film, but he does in the books and even helps Sirius. The cat knew how to enter the Shrieking Shack by poking a knot in the tree and paralyzing it.
32. In the book, Ron is generally depicted as being brave and heroic under stress while Hermione is depicted as being nervous, terrified/frightened.
33. In the book, Harry never saw Pettigrew's name on the Marauder's map, and Lupin was the one who saw it after acquiring the map and using it on the same day as Buckbeak's execution since he knew Harry, Ron, and Hermione would visit Hagrid that day. These events are what caused Lupin to believe that Sirius is innocent.
34. In the book, Harry, Ron, and Hermione all try and disarm Snape at the same time, causing him to hit against the wall and go unconscious.
35. In the book, Snape stays unconscious due to the spell cast by Hermione, Ron, and Harry and has to be suspended in mid-air by magic to be brought out of the Shrieking Shack. He never tried to save the trio by shielding them from Lupin.
36. In the book, Hermione is with Harry and Sirius when they are attacked by the Dementors. Ron was stunned unconscious by Peter Pettigrew with Lupin's wand.
37. Dumbledore tells Harry and Hermione that Sirius is locked up in Professor Flitwick's office in the West Tower, a thirteenth window from the right of the tower.
38. The part where Ron received an owl from Sirius Black to replace Scabbers has been omitted. Ginny named the Owl as Pigwidgeon.
39. The letter addressed to Harry that Sirius sent with Pigwidgeon which gave him visitation rights to enter Hogsmeade was omitted.
40. Harry meets his Uncle Vernon on the platform at King's Cross station. He tells his uncle that he has a godfather, who has escaped from wizard prison, which terrifies the Dursleys

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Goblet of Fire

1. The book starts with the whole story about the murder of the Riddle family and Frank Bryce the gardener.
2. Frank Bryce is invited into the room by Voldemort and his servants, and he confronts them shortly before he is killed.
3. Bertha Jorkins was mentioned in the book.
4. Harry wakes up at Privet Drive, 2 weeks before September 1st. He used to terrify his uncle and aunt by the name of his criminal godfather and even used this trick to convince them to let him go to the Quidditch World Cup. The Weasleys enter Privet Drive through the fireplace, as Harry receives an invitation from the Weasleys to the Quidditch World Cup. Fred and George give Dudley Ton-Tongue Toffee due to which Arthur scolds them at the burrow.
5. Winky the house elf of B. Crouch Sr. was found unconscious near the place from where the dark mark was conjured. The mark was conjured using Harry's wand which he lost in the Quidditch World Cup. Winky starts drinking nonstop after she gets fired by her master and Dobby helps her to get work at Hogwarts.
6. Harry sends a letter to Sirius to let him know that his scar hurts, and his concerns about Voldemort being nearby.
7. Bill and Charlie Weasley arrive at the Burrow too.
8. Fred and George always worked secretly discussing something which we get to know about their new business of Weasley's wizard wheezes.
9. In the book, the whole Quidditch game is shown. The Bulgarians show the Veelas as their mascots.
10. Hagrid had lessons with nifflers, blast ended skrewts.
11. Hogwarts kitchen with the house elves is shown and even the way to enter the kitchen too.
12. Percy works with the ministry, under Barty Crouch Sr.
13. In the book, students from Beauxbatons and Durmstrang arrive on Halloween night. They don't perform in front of the students of Hogwarts. The Hogwarts students welcome the Durmstrang students and Beuxbaton students. It is clearly stated in the books the way they enter Hogwarts through air and water.
14. Beauxbatons was a co-ed school with male students too.
15. Igor Karkaroff follows Madame Maxime and Hagrid to see the dragons. Charlie Weasley was the one to bring the Dragons to Hogwarts.
16. Dumbledore CALMLY asks Harry if he put his name in the Goblet of Fire.
17. Hermione creates a House Elves’ protection campaign S.P.E.W. to get the house elves the respect and wages they deserve.
18. Dobby gives Harry the Gillyweed. Neville was supposed to do that as Alastor Moody provides Neville with a book of Herbology but it doesn’t click to Neville that he may become a help to Harry for the second task. Then Dobby helps Harry.
19. When Harry is returning from the Prefects' Bathroom, he trips on the missing step and drops his egg down the stairs, causing his egg to open and make a giant shrieking sound. Filch arrives and thinks that Peeves stole the egg. Mad-Eye and Snape then arrive and the three start talking. Moody’s Magical eye can look through the invisibility cloaks.
20. Barty Crouch Sr. eventually becomes mad and sends Percy to his meetings instead of going himself. Barty Crouch Jr. never had the habit of clicking his tongue out.
21. Barty Crouch Sr. even attacks Krum.
22. Solving the Riddle of sphinx, fighting a boggart and blast-ended skrewts was a part of the third task in the maze.
23. Barty Crouch Jr. explains to everyone the truth after consuming the Veritaserum how he replaced himself with his mother in the prison and his mother lived there with the consumption of polyjuice potion and eventually died. How he was forced to be under his father's imprisonment in his house, with Winky the house elf who took care of him. How he escaped his father, conjured the dark mark in the World Cup by stealing Harry's wand, slowly turned his father mad, killed his father transfigured his body into a bone and buried it. B. Crouch Jr. was kissed by the dementors in the end “accidentally” which results in his death.
24. Harry gives his 1000 galleons prize money to the Weasley twins for their joke shop business and insists they not tell anyone about it.

The Order Of Phoenix

1. Hagrid tells everyone about Thestrals during a Care of Magical Creatures lesson.
2. Ron becomes Keeper. Angelina Johnson becomes Gryffindor Quidditch captain. Harry and George are banned from ever playing Quidditch again by Professor Umbridge because they attacked Malfoy after being provoked ( he insulted their mothers). Fred is also banned because he was going to punch Malfoy but was held back. Ginny becomes the seeker after Harry is banned.
3. Dumbledore has a quick duel with Cornelius Fudge and some Aurors before he leaves the school.
4. In the duel between Dumbledore and Voldemort, Dumbledore transfigures the statues into life at the MOM and even Fawks help him there.
5. The rooms in the department of ministries were cut off. Ron was strangled by the tentacles of floating brains in one of the rooms due to which he got lifetime scars on his arms.
6. Harry is so upset by Sirius's death that he destroys Dumbledore's office. Dumbledore just stands there and watches him calmly.
7. Marietta Edgecombe was the one to reveal Dumbledore's army to Umbridge for which she also got boils on her face as punishment for betraying the DA.
8. Hermione caged Rita Skeeter as a beetle in a jar in the last term. She releases her here with a condition to publish the actual story of “Harry's confrontation with Voldemort at Little Hangleton” in the Daily Prophet.
9. Harry goes on a date with Cho Chang before the interview on Valentine’s Day at Madam Pudifoot’s tea shop, but all creates a mess when Cho rushes out aggressively upon learning that Harry is about to meet Hermione after this.
10. Ron and Hermione become prefects.
11. Not only one but several howlers are sent to the Dursleys by the ministry and Dumbledore when Dudley and Harry are attacked by dementors.
12. Fred and George leave the school by summoning their broomsticks which were chained up in Umbridge's office. They even give a job to Peeves to create chaos for Umbridge continuously. But they didn’t do this during the OWL’s Exam.
13. Neville's parents became mentally ill due to the Cruciatus curse by Bellatrix Lestrange. They were in St. Mungo's. Harry knew this fact as Dumbledore told him but he didn't tell anyone. Later when they went to visit Arthur Weasley at St. Mungo's, they met Neville, his parents and his grandmother too.
14. At St. Mungo's, they even met Gilderoy Lockhart who lost his memories in the second book.
15. McGonagall was attacked by three stunning spells straight on her chest while she was protecting Hagrid from the Aurors as they were forcing him out of Hogwarts on Umbridge's orders.
16. Peeves kicked Umbridge from the school by hitting her with McGonagall’s stick which she lent him for this task.
17. After Fred and George left the school Lee Jordon left Nifflers in Umbridge's office 2 times.
18. Flitwick, Sprout and McGonagall thoroughly enjoyed the chaos created at the school by students and Peeves to irritate Umbridge on her first day as headmistress. Even the Gargoyle refused to open the Headmaster's office for her. McGonagall even helped Peeves sometimes by telling him how to unscrew the chandelier on Umbridge's head.
19. Harry was unable to hear the prophecy as Neville accidentally broke it. Later Dumbledore told him through the Pensive and that he was the one who heard the whole prophecy himself. He even mentions that Neville may have been the chosen one instead of Harry but Voldemort chose Harry. And he even apologizes to him that he hid such an important thing from Harry all this time. He swears that he’s gonna tell Harry and everything now. Dumbledore even cries a bit accepting that he’s not at all perfect and this old man has committed many mistakes.
20. Trelawney was the one who made the prophecy that a boy born at the end of July would destroy Voldemort. It was either Harry or Neville. But Voldemort chose Harry as his mortal enemy.
21. After the forbidden forest incident, Umbridge was sent to the hospital wing where she gasped for every minute sound made as she was terrified of the Centaurs.
22. Kreacher lies to Harry about Sirius not being at home (Grimmauld Place) when Harry tries and check on Sirius after having a vision of Voldemort torturing Sirius at the Ministry. Harry checks about Sirius through the floo fire from Umbridge's office as the ministry seals all other floo networks except for Umbridge's office. When he gets assured that Sirius is not at home then he decides to go to the Ministry of Magic.

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Half-blood Prince

1. The Brockdale Bridge was destroyed by the Death Eaters, with around fifty Muggles being killed.
2. Cornelius Fudge discussed the murders, hurricanes, and bridge collapse with the Muggle Prime Minister, as well as the former's resignation as Minister of Magic, and Rufus Scrimgeour introducing himself to the latter.
3. Bellatrix and Narcissa are met at the door by Snape, who then brings them to the parlour. Peter Pettigrew is then called in to bring them drinks. He does so and then hurries upstairs to listen by a door, which Snape says is a new habit he has taken up.
4. Bellatrix kills a fox before walking towards Snape's residence.
5. Dumbledore comes for Harry at Privet Drive as he had pre-arranged in a letter, having a cup of tea and conversing with the Dursleys before heading off with Harry. Harry inherited Grimmauld Place and Kreacher after Sirius Black's death.
6. Ministry issued a pamphlet showing the Safety measures including information about inferi too.
7. Hagrid got Buckbeak back with a new name Witherwings.
8. While at the Dursley's house, Harry carries the owl cage and his trunk out, when Dumbledore tells him that they don't want to be bothered with the luggage, and says he will send them to the Burrow. Dumbledore then waves his wand to make the owl and trunk vanish, and he and Harry set out to collect Slughorn.
9. Dumbledore and Harry apparate to the tool shed near the Burrow. Before leaving him, Dumbledore informs Harry that he will be giving him private lessons and tells him to confide the truth about the prophecy to Ron and Hermione as well as to keep his invisibility cloak with him at all times.
10. Harry arrives at the Burrow around 1:00 a.m., after Ron and Hermione have gone to bed, and they don't see him until the next morning.
11. Molly Weasley and Tonks see Harry first, meeting him at the door as Dumbledore leaves him in their care. Tonks was not the same after Sirius’s death. She becomes calm and a bit depressed after that, as he was her cousin after all.
12. Arthur Weasley got a promotion. Bill and Fleaur's wedding was fixed for the next year. Molly and Ginny never liked Fleur. Ginny called Fleaur a Phelgm and Molly wanted Nymphadora Tonks to be the bride for Bill.
13. Security measures were implied outside the Burrow for Harry's safety.
14. The trio's O.W.L.s results came to them by owl.
15. Igor Karkaroff was murdered by Voldemort.
16. The trio meet Narcissa and Draco Malfoy at Madam Malkin's robe shop where Harry had a little row with Mrs. Malfoy.
17. Ginny buys a pygmy puff from her brother's joke shop as her pet and names it Arnold.
18. Draco sneaks off on his own to Borgin and Burkes to talk about the Vanishing Cabinet. Harry, Ron and Hermione sneak out from the Weasley’s shop using an invisibility cloak to follow Malfoy. Hermione tries to get information about Draco and what was he talking about in the Borgin and Burkes after Draco departs from there. But the owner of the shop drove her away from there.
19. Harry asks if he could share a compartment with Ginny on the train, but she says that she has to go and see Dean, and Harry shares a compartment with Neville and Luna instead.
20. The Slug Club's first meeting takes place in Slughorn's compartment in the Hogwarts Express.
21. Harry follows Blaise Zabini into Slytherin's car while being under his invisibility cloak.
22. Draco criticises Professor Slughorn and his Slug Club members with Pansy and Blaise, then talks to them about how he may not return to school for the next year, saying he has to do other things.
23. Tonks finds Harry petrified in the train and not Luna, stating that she did not see him leave the train and, knowing Harry has his cloak, decides to double-check the train.
24. Snape meets Harry at the Castle gates taking him with him to the Castle.
25. Harry notices that Tonks's patronus is changed and is large with four legs.
26. When Harry entered the Great Hall, his nose was bleeding as Draco kicked him on the train, and Hermione performed the Tergeo spell to heal it.
27. When Harry entered the Great Hall, he still wore his normal clothes because he didn't get enough time to change into his robes.
28. When Dumbledore speaks in the Great Hall, Hermione asks about his injured hand, and many others start to whisper upon seeing it. Dumbledore dismisses it, saying it's nothing to worry about, and covers it with his sleeve.
29. Harry, Ron, and Hermione are the only Gryffindor students to take Slughorn's N.E.W.T. Potions class.
30. The Felix Felicis is gold in colour.
31. The Gaunt scene, the way Tom Riddle reached the orphanage and how Merope Gaunt died were cut in the films. It's a very long story though. You may read the book for the detailed story.
32. The Resurrection Stone mounted on the ring is cracked down from the middle, right through the symbol of the Deathly Hallows.
33. Harry, Hermione, and Ron had seen very little of Hagrid for some time. He had not been attending meals and was not seen around the school very much, and whenever they did see Hagrid, he would fail to acknowledge them. Finally, the three visits Hagrid at his hut, and notice he has a barrel of foot-long maggots, which he tells them is food for Aragog. Hagrid goes on to tell Harry, Hermione, and Ron that Aragog got sick over the summer and was not getting any better, and Hagrid fears Aragog may be dying.
34. When Slughorn finds Harry in Honeydukes, he tells Harry that he had missed the third supper party that Slughorn held (as Harry always held Quidditch practice whenever they were held) and invites him to another.
35. Hagrid comes and takes Katie to the castle when she gets sick after touching the cursed necklace. While Leane cries harder than ever telling McGonagall all about the accident. When Harry is asked what evidence he has that Draco cursed Katie, in the book, he tells McGonagall about how he, Hermione, and Ron followed Draco to Borkin and Burkes.
36. Harry finds Mundungus near three broomsticks smuggling Sirius's possessions and he hits Mundungus, to tell the truth when Tonks stops them and Mundungus apparates.
37. Hermione was the one to notice and scold Harry for putting Felix Felicis in Ron's drink.
38. The weather on the day of the first Quidditch match was clear, a circumstance which Ron attributes to the Felix Felicis he thinks he drank.
39. Ron and Ginny had a fight when Ginny told Ron that Hermione might have kissed Viktor, Harry kissed Cho then why she shouldn't kiss Dean.
40. Remus Lupin reveals to Harry that Snape helped him while he taught at Hogwarts as a D.A.D.A. professor by brewing him Wolfsbane Potion every month when the trio went to The Burrow at Christmas.
41. Percy Weasley arrives at the Burrow on Christmas Day with the new Minister of Magic, Rufus Scrimgeour. Scrimgeour attempts to persuade Harry to help the Ministry to tell the Wizarding world that the Ministry's doing a wonderful job and Harry rejects it.
42. Stan Shunpike, the conductor of The Knight bus, was imprisoned at Azkaban guilty of working for Voldemort.
43. Ron gets a Christmas present at The Burrow by Lavender. A gold chain with visible words 'My Sweetheart' written on it as a pendant.
44. Apparition lessons are conducted and taught by Wilkie Twycross. Apparition tests and examinations are also conducted which Harry was not able to attempt as he was not 17 yet.
45. Ron and Lavender break up due to Lavender sees Ron and Hermione coming down from the boys' dormitory (not seeing Harry due to him hiding under his invisibility cloak) and assumes they are together.
46. Ron consumes love potion chocolate cauldrons on his birthday and not on Valentine's Day.
47. Slughorn later tells Harry that he has had every bottle tested by a house elf since Ron's incident.
48. Luna Lovegood sits for commentary for the next Quidditch match which Ron enjoys listening to from the Hospital wing.
49. Hagrid, Fred, George, Arthur & Molly Weasley visit Ron in the Hospital wing. Then praising for Harry using a bezoar as an antidote to the poison was mentioned by Fred.
50. The memories of Hepzibah Smith and Hokey were not in the films.
51. Harry noticed Malfoy disappearing from the Marauder's Map when he entered the Room of Requirement. Crabbe and Goyle used Polyjuice Potion and stood guard for Malfoy outside of the Room of Requirement.
52. The trio received a letter from Hagrid informing them that Aragog was dead.
53. According to Dumbledore's guesswork, he worked out that the cup and the locket were the Horcruxes too. Even he mentioned that he thinks that now Nagini was also one of the Horcruxes. As Gaunt's and Hokey's memories were cut off from the movies, it was unclear.
54. Harry was tailing Draco using the Marauder's Map until he saw Draco inside the Boy's bathroom on the sixth floor. He overheard Draco crying and saw that he was accompanied by Moaning Myrtle, who at times heard the boy cry his eyes out in the bathroom.
55. Harry hid the Half-blood Prince book in the Room of requirement dreading the consequences if Snape got the hold of the book. He even glanced at a dummy wearing a crown-like thing in there. He took Ron's potions book in which Ron wrote his name with the spell check quills bought from his brother's joke shop. The spell check quiz instead messed up with the spellings which resulted in Ron's name in the Potions book to spell as Roonil Walzib. When Snape asked Harry about the unusual name, Harry lied that it was his new nickname. This incident took place in Moaning Myrtle's bathroom after Malfoy went all bloody to the Hospital wing.
56. Ginny kisses Harry after he comes back from the Quidditch match with the Quidditch cup in the Common room in front of everyone.
57. Sybill tells Harry that she heard someone laugh in the room of requirement and when she tried to find out who was there, she was thrown out by someone. This happens the moment when Harry is on his way to Dumbledore's office as he called Harry.
58. Dumbledore tells Harry to meet him in 5 minutes to start their Horcrux hunt when Harry rushes to the common room, firstly gives the rest of the Felix Felicis to Hermione and Ron before meeting Dumbledore and tells them to stand guard near the Room of Requirement and call the Order if there's anything fishy, because he suspected that Malfoy was about to do something dangerous.
59. The Burrow was NOT BURNT down by the Death eaters.
60. Dumbledore and Harry (who was under the invisibility cloak) walk to the Hog's Head in the village of Hogsmeade, from where they Disapparate to the cave.
61. Harry and Dumbledore had to swim from the rock until they arrived at the cave entrance. Once in the cave, Dumbledore ponders about how to access the hideout.
62. Dumbledore attempts to reach into the potion to grab the Horcrux, but an invisible barrier prevents him from penetrating the potion and he realizes that the potion cannot be penetrated by conventional means and begins pondering about how to reach the Horcrux. The potion was of flashy green colour.
63. When Harry tries to get Dumbledore water from the basin, he fills the cup, but the cup becomes empty by the time he gets it to Dumbledore.
64. Dumbledore trapped the inferiors on the island with a lasso of fire. Dumbledore was left in a considerably weakened state after drinking the potion, which continued up to his death.
65. Dumbledore instructed Harry to call Professor Snape and when he ran near the door knob he was frozen by Dumbledore’s spell on the spot. He was under the invisibility cloak then, thus unable to get spotted by Snape or the Death eaters.
66. A war took place in the castle during Dumbledore's death between the order members, professors and the death eaters.
67. Bill Weasley here got attacked by Greyback. Harry tried to use the Cruciatus Curse on Snape.
68. Harry opened the false locket when he was sitting by the deceased Dumbledore, noticing it was smaller than the one seen in the memory (omitted from the film), and lacked the distinct Slytherin "S" symbol. He then opened it, and read it. Dumbledore appeared to be bleeding from his mouth after being killed, and Harry wiped off the blood with his (Harry's) own sleeve as he knelt by the headmaster's body. Fawkes after some time started singing, grieving for Dumbledore.
69. Ginny took Harry to the Hospital wing where Bill with a scarred face lay on the bed. And here Fleur fought with Molly that she still was going to marry Bill. Here, Harry got to know that Tonks insisted on marrying Remus for a long time.
70. A debate took place in the Headmaster's office whether to bury Dumbledore's body in the Grounds of Hogwarts or not.
71. The whole funeral ceremony takes place with mourning songs by merepeople and Centaurs paying respect to Dumbledore.
72. Harry takes the help of Kreacher and Dobby to get to know about the whereabouts of Malfoy throughout the whole book.

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Finally, The Deathly Hallows

1. The movie pretty much begins with Harry leaving Number 4 Private Drive for the final time, with members of the Order of the Phoenix and Hogwarts school friends coming to help him get away. However, as they up their brooms with six others disguised as Harry, a fight with Lord Voldemort and his Death Eaters breaks out.
2. In the book, they're able to spot the real Potter after he uses Expelliarmus on Stan Shunpike. Yet this is changed for the movie, with Hedwig's loyalty to him giving him away instead.
3. In the Deathly Hallows novel, Harry and Hagrid land at Nymphadora Tonks' house before going to The Burrow. The Order planned that it was best to split up so that, in the worst-case scenario, there would be at least some survivors. Harry met Andromeda Tonks (Nymphadora’s Mother) there and mistook her to be Bellatrix due to her resemblance with her sister. But then he realized that Andromeda had brownish hair and she had pretty much a kind and warm expression on her face compared to Bellatrix. But the movie has everyone going straight to the Burrow, with Harry and Hagrid crash-landing in their back garden. In the book, the members of the Order even argued with Harry in the burrow when he told them that his wand worked on its own during his fight with Voldemort and others didn’t believe him as a wand never works on its own accord.
4. After getting to The Burrow, Harry has his mind taken off his ongoing battle against Lord Voldemort due to Fleur Delacour and Billy Weasley's wedding. Molly tries her best to keep the trio busy and not let them meet each other as she doubts that they are up to something about Voldemort.
5. Fleaur's family members visit the burrow for the wedding and Ginny gets jealous of Gabrielle Delacour as she continuously tries to glace at Harry. When it comes to the main event, the blockbuster shows Harry wandering around freely as himself without a care in the world. Things are different in the source material, though, with the Boy Who Lived using Polyjuice to conceal his appearance. He becomes a red-headed Muggle boy (as Barry Weasley, another cousin of Weasleys), with Fred and George Weasley secretly obtaining the hairs from a random boy without him knowing.
6. After fleeing the wedding in the movie, Harry, Ron and Hermione all end up taking refuge at Grimmauld Place, despite the risk that Severus Snape and his fellow Death Eaters could burst in at any moment. It's only the trio who were ever there - with a weird, cursed Albus Dumbledore trap.
7. In the book, however, Remus Lupin goes there. He begs Harry, Ron and Hermione to let him join them on their quest to defeat Voldemort, despite being with Nymphadora Tonks and having a child on the way. A row breaks out between him and Harry and Lupin leaves, but he's barely in the film at all.
8. Even Kreacher was changed and became more kind towards the trio after Harry gifted Kreacher the fake Slytherin’s locket as a memorial of his late Master Regulus Black. The story of Regulus Black being a death eater, him becoming aware of his mistakes, Voldemort making Kreacher drink the potion to hide the Slytherin’s locket in the cave, R.A.B replacing the fake locket with the actual Slytherin’s locket and his death in the hands of infer was omitted from the movie.
9. Harry, Ron and Hermione make “Breaking into the Ministry of Magic” look relatively easy during the movie. It's almost as if they thought of the plan and then decided to execute it immediately on the same day.
10. But this is different in the source material as well. It takes them a long time and lots of planning before they muster up the courage to make the trip to the very place that wants them dead the most. Before leaving Grimmauld Place, Hermione takes Phineas Nigellus Black’s Picture frame in her ever-extendible bag as she finds it dangerous to leave it there as proof for the Death eaters to find them. After a while, during their run, they use the frame to get the whereabouts of Dumbledore’s army.
11. Harry and Hermione sadly look over the remains of Godric's Hollow. What makes it much more tragic is that there's a tribute and mural to James and Lily Potter with messages of support from many members of the magical community. This leads Harry to shed a few tears and, had it made the movie, the same could be said for audience members.
12. One thing the movie changed from the books that we really, really like is the soft dance scene between Harry and Hermione inside their tent while on the run. It's genuinely poignant as they waltz around, smiling and bringing some genuine happiness to a dark movie. It also makes Ron's Horcrux vision, when he sees the duo kissing, more sympathetic. His feelings of jealousy are understandable but misplaced, with Harry's heart belonging to Ginny. In the book though, Hermione spends sleepless weeping nights thinking that Harry was unable to hear her weeps. There were days and nights in a row that they didn’t even utter a word to each other.
13. Harry and Hermione are reunited with Ron in the movie when he comes to the Boy Who Lived's rescue by defeating Lord Voldemort's Locket. A little while after, however, they're captured by Snatchers. When Ron comes back, he tells them that the name of Voldemort is now taboo and speaking his name will get the Death eaters to the speaker’s location. Which somehow happens by mistake and the snatchers find their location.
14. In the big screen version of The Deathly Hallows, this is dragged out a bit, with Warner Bros choosing to make it an action-packed scene instead, full of running and spell-casting. They have a lot less time in the book, though, with Hermione only just managing to disguise Harry quickly.
15. That isn't the only difference when it comes to Snatchers. In the book, Dean Thomas is also captured and brought with Harry, Ron and Hermione to Malfoy Manor for interrogation at the hands of Bellatrix Lestrange - although he's shoved in the cellar for the most part. Hermione was tortured by Bellatrix using the Cruciatus curse on her. Mudblood was NOT carved on her arm.
16. While the Harry Potter movies did a good job at managing to cram in pretty much every shocking and emotional death, they somewhat bizarrely chose to omit Peter Pettigrew's fatal incident.
17. The movie shows him being cursed by Harry and Ron as they plot to break free of the cellar at Malfoy Manor. What it doesn't show, though, is Pettigrew's silver hand (the one given to him by Lord Voldemort in the Goblet of Fire), choking him to death. It does this because he hesitates in serving his master at that moment and is considering to side with Harry. This shows just how ruthless, callous and organized the Dark Lord can be.
18. The 2nd part of the movie begins at Shell Cottage, the home of the recently married Bill Weasley and Fleur Delacour. The previous instalment had ended with the death of Dobby and Harry, along with Ron, Hermione and Griphook the Goblin, who wasted no time in plotting their break-in on Gringotts.
19. In the book, though, there's some light in the darkness. Remus Lupin and Nymphadora Tonks have a child named Teddy Lupin, with Harry being given the responsibility of being his godfather. This is all cut from the film, though, with Teddy never being mentioned and Lupin and Tonks only appearing during the Battle of Hogwarts. The trio spends weeks plotting the Gringott's break-in with Griphook. Fleur and Bill don’t pretty much like Griphooks’s behaviour but still let him be at their home. Bill even warns Harry about working with Griphook as Goblins can’t be trusted by wizards. Ollivander was sent to his home safely afterwards and even Luna made a great bond with Ollivander in the meantime. The trio with Griphook, silently leave the Shell Cottage for Gringotts under the Cloak leaving a letter for Bill and Fleaur informing the start of the next run for Voldemort.
20. In the Vault of Lestrange, the possessions were spellbound in a way that they will be doubled with the human touch (which was of course there in the movies) but they even cause burns on the skin of the one touching them.
21. Like the movies, it never actually pains Harry or Voldemort after a Horcrux is destroyed. Voldemort didn’t even realize that Harry was after his Horcruxes until he got to know about the Hufflepuff’s cup’s theft from the Gringotts. He then panics and thinks about the Horcrux in Hogwarts and starts to check every Horcrux’s safety. As Harry can read Voldemort’s mind, he gets to know that the last Horcrux is at Hogwarts and it belongs to Ravenclaw after he jumps off from the giant dragon which they rode to escape from Gringotts.
22. Harry, Ron and Hermione decide that they need to get to Hogwarts following their successful assault on Bellatrix Lestrange's Gringotts’ vault - and opt to do so via Hogsmeade. But accidentally they set off the alarm, though, and Aberforth Dumbledore comes to their rescue. Aberforth then tells the trio about his, Dumbledore’s and Grindelwald's past and Ariana’s death. He even confronts the death eaters by lying that the 4 legged patronus they saw was his goat and not Harry’s Stag.
23. In the blockbuster, Aberforth makes references to Dumbledore's shady past, implying that he let his greed get in the way of looking after his sister Ariana. The source material, though, has a far deeper story. Ariana is attacked by Muggles and, years later, dies in the middle of a fight between Albus and Gellert Grindelwald.
24. Neville tells Harry that his grandmother was on a run too as she hit a death eater badly while they came to her to interrogate her.
25. Ah, this is a scene we wished had been included. In Rowling's novel, Harry asks the Hogwarts students about any valuable possession of Ravenclaw and Ron suggests he let the others help him find it. Cho then tells Harry about the lost Diadem and asks him to let her help him go to the Ravenclaw Common room. Ginny then makes Luna go with Harry and tells Cho that Luna will help Harry out. Harry and Luna Lovegood sneak into Ravenclaw Tower as they hunt for a Diadem that had been turned into a Horcrux by Lord Voldemort. Death Eater Amycus Carrow suspects this, though, and goes to try and stop them.
26. Harry and Luna manage to hide under the invisibility cloak and Carrow's screams alert Minerva McGonagall, who goes there. When Carrow spits on her face, however, Harry leaps into action and knocks him out with the Cruciatus curse and then realizes Bellatrix’s saying that a person must mean to hurt the other while using the Cruciatus curse. That, certainly, would have been awesome to see.
27. The destruction of Helga Hufflepuff’s cup in the books was not mentioned as the whole plot was from Harry’s POV. But Harry meets Ron and Hermione after a long time after he departs from the ROR with Luna to the Ravenclaw common room. There he gets to know that the Cup has been destroyed by Hermione and they even got a couple of Basilisk fangs with them from the Chamber too. Here is the moment when Ron says that they should help the house elves out from there as they don’t want more of Dobby’s, and Hermione drops the fangs from her hand, jumps on Ron and Kisses him. Harry gets annoyed by the situation and yells “Is this the moment? Oi!! There’s a war going on here.”
28. How we wish Fred Weasley had survived. His death is tinkered with for the movie version of the story, showing a witch standing over him. This gives the impression that he was killed in combat.
29. It's different in the book, though, with Fred perishing when an explosion hits Hogwarts hard. He dies with a smile on his face and with recently-redeemed Percy by his side. Perhaps it's for the best they altered it - it would have probably made the audience weep even more than they already did.
30. When Harry watches Snape’s memories in the Pensieve he watches Snape talking to Headmaster Dumbledore’s picture frame about Harry, their plan of making Mundungus Fletcher become the one to suggest the idea of seven potters to the order, Phineas Nigellus Black telling them about the whereabouts of the trio, Snape departing to place the sword of Griffindor near the place where the trio was staying.
31. Ron and Hermione never knew that Harry was supposed to die as Harry never met them after he saw the truth through Snape's memories in the Pensieve. He just chose not to meet them and silently went to the forbidden forest as he knew that they would never let him go meet his death. He met Neville on his way to the forest. Neville sensed Harry near him as Harry was under his invisibility cloak. Harry tells Neville that in case Neville sees a giant snake with Voldemort he is supposed to kill or slash it as it's important and Neville says that he'll keep this in mind.
32. In the original version of the story, Voldemort freezes Neville before placing a flaming Sorting Hat on his head. This would be excruciating and agony to bear. Instead, the movie merely shows the Dark Lord sending him flying in a fit of rage when he discovers Harry is alive - despite casting the killing curse at him for a second time. Voldemort makes Hagrid put Harry near his feet when he is unconscious. Hagrid does so and when the right time strikes, Harry slowly takes the invisibility cloak out of his coat and disappears. He mysteriously sends curses and strikes the death eaters while hiding under the cloak. Voldemort then realizes that Harry’s Body is gone. The deleted scene from the movie in which Malfoy throws his wand towards Harry to help him doesn’t happen in books. Everyone in the school realizes that Harry’s alive when Harry protects Molly from Voldemort’s Death curse after Molly killed Bellatrix. He takes off his cloak in front of everyone.
33. Bellatrix Lestrange is a repulsive character and, while we wouldn't wish harm on anybody, let's just say that she deserved her comeuppance at Molly Weasley's hand. In the movie, she dies via a bizarre old curse that sees her age before combusting into loads of small black bits.
34. But it’s better handled in the book. Mrs Weasley's curse strikes her in the chest and she dies with a laughing look on her face, echoing the same death of her cousin, Sirius Black, who was killed by the Death Eater in the Order of the Phoenix two years ago.
35. It would have been awesome to see his three-way duel with Voldemort with Minerva McGonagall, Horace Slughorn and Kingsley Shacklebolt. It would have been extra good to see Slughorn fighting the man he once taught when the villain was Tom Riddle. Alas, it wasn't to be. The book even showed that Ron was the one to kill Greyback along with Neville.
36. Voldemort dies in the courtyard in the Deathly Hallows: Part 2 movie. We assume everybody else is fighting each other in the castle itself - because there's absolutely nobody around. He disintegrates after his killing curse ends up consuming him thanks to some trickery involving the Elder wand.
37. But, in the book, he dies in front of everyone inside the Great Hall. People stand around and watch his and Harry's final confrontation showing that after all, Voldemort was a mere wizard with a normal death- and then the mob celebrates the Boy Who Lived in a moment of sheer, magical triumph.
38. The movie shows Lucius Malfoy, Narcissa Malfoy and Draco Malfoy all fleeing from the scene after the end of the Battle of Hogwarts, never to be seen again. In the source material, though, they're present at Hogwarts for the post-war celebrations.
39. And that's not the only thing that's altered. Warner Bros chose to skip any mention of Kingsley Shacklebolt becoming emergency Minister of Magic, the Death Eaters being rounded up and the innocents being freed from Azkaban. The movie ends rather abruptly but, despite that, it's still one of the series.
40. While there are many people present for the Battle of Hogwarts, there are also plenty of people who don't show up in the movie - but do in the books.
41. Colin Creevey, his brother Denjis Creevey, Augusta Longbottom, Ted Tonks, Grawp, Oliver Wood, Charlie Weasley and many more are present in the book. Even the House Elves of Hogwarts helped in the War by fighting the death eaters. Sadly Colin Creevey died in the battle.
42. The trio went to the Headmaster’s office after the war. There, Harry mentions to Dumbledore’s frame that he dropped the resurrection stone in the forest and he wants to place the Elder Wand back in Dumbledore’s Tomb. Harry uses an Elder wand to repair his broken Pheonix feather core wand successfully. He never BROKE THE WAND.
43. In the epilogue, Lily Luna Potter discovers Teddy Tonks kissing a girl in the station and tells this to her parents. After which Ginny says that let him be.
44. Neville becomes a Herbology professor at Hogwarts.

Thank you for scrolling with such patience but I tried to mention almost every difference here. Hope you liked it and please upvote.

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