From where I see it, there is no difference between the two. They both were enlightened Shramana masters. Jina - The Mahavira was the last and 24th Tirthankara (Ford-maker) of the Shramana tradition and Gautama - The Buddha its brightest star ever because of whom this tradition is now well known across the globe.
However, this answer will not go well with the followers of Jainism and with those of Buddhism as each of the followers regards their own master to be completely enlightened and the other as a heretic preacher.
Thus, to justify my answer, I will try and explain in detail in below two sections. Please pardon me for the long answer, but it's important so that I may not be accused of Mithyatya or Wrong-Insight by either of the two groups for comparing two assumed unequal as equal.
In the first section, I will discuss what general believers of Jainism and Buddhism believe about the masters of the opposite creed and the probable reasons for the same, and then explain why these assumptions are wrong.
In the second section, I will explain whether two completely enlightened masters can co-exist as per the Shramana school - the mother of both traditions.
1st Section:
What do Buddhist annals claim of Jina?
Jina is referred to as one of the six great contemporaries of Buddha. He is often associated with one of the extreme wings of various Shramana schools that existed during the time of Buddha and is thus claimed as faulty.
Nothing could be further than truth as Jina unequivocally denounced such practices.
Further, a lot of Buddhist annals associate a lot of philosophies with Jina that were never a part of His teachings.
Say for eg, Majjhima Nikaya 1, Saccaka, has been shown to be a Jain monk - the follower of ‘Nigan.tha’. This is not true, for neither his philosophy is in tune with the message of Jina, nor is his description or lifestyle in tune with that of Jain monks. Below are a few examples.
- Saccaka claims his material body, feelings, perceptions, etc to be his true self. This is not so as per Jainism. Body and bodily properties made of matter are referred to as "Pudgal" (matter) which is one of the six fundamental substances (Dravya) of the universe. The concept of self in Jainism is referred to as "Jiva". This is another of the six fundamental substances that constitute the universe. It means "The Being" or "Soul" which is caught in the cycle of transmigration till it achieves Moksha. No follower of Jainism would ever equate pudgal (matter) that the body or mind is made off with Jiva or soul.
- Saccaka prepared food in His own monastery. The fact is that Jain monks do not cook or even live in resident monasteries even till today i.e. 2600 years after Jina.
- He invites Buddha and his disciples for a meal and asks Licchivies to bring a meal. Jain monks never ask anyone to bring a meal but beg for alms for themselves or their peers. They never ask for food to be brought for themselves or any guest.
- He is supposed to have hair, while Jain monks did not have any. (They pulled them out by their own hands (loch)).
Thus, one thing that can be said for sure is that Nigantha in Buddhist annals may not always be the same person as Jina. It's possible that this is being referred to some other person. It's worth noting that Mikkhali Goshala, another of the illustrious six contemporaries of Buddha also roamed nude and thus was Nigantha. He was the founder of the Ajivika sect and very little is known about that tradition now as it has gone extinct. The Nigantha used in the Buddhist annals might have also been used for Him or the sutras like above may have been purposefully cooked by Buddhists to present Jina in a bad light to make for themselves a superior position in Shramana circles.
Another example of these cooked-up annals is the Upali Sutta, which states:
"Mahavira (Jina) became very grief-stricken after hearing that one of his favorite disciples (Upali) had decided to follow Buddha. He vomited hot blood and died shortly after that".
Jina preached the path of "vit-ragi", i.e. a state of mind where one transcends all attachments. This is essential for a seeker to achieve complete enlightenment (Keval-Gyan). It's so evident in the message of Jina that He once told His chief disciple "Gautama" that the reason for his not achieving enlightenment is his attachment to Himself (Jina).
It's hilarious to read that such a Master is being represented as so much attached to a lay follower that He could not withstand his conversion to Buddhism and thus "became very grief-stricken" and vomited to death.
Thus, to sum up, it may be said that Jina is not presented in the right colors in Buddhist annals and that to understand what He stood for, a thorough understanding of Jain annals is a must.
What do Jains feel about Buddha?
Buddha in Jain annals has been referred to as "Mahatma" which means a great soul. However, as He deviated (or appeared to be deviating) from two of the fundamental precepts of Jainism, He is often denounced as having gone astray.
These precepts are as under:
1. Non believe in the concept of self or soul.
The Buddhist philosophy of "anatta" has often been translated as "No-Self" and thus its claimed that Buddha denounced the existence of the soul. However, on close examination of the suttas that describe "Anatta" it's observed that what anatta really means is "not self" and not "no self".
The suttas that define Anatta do so to explain the concepts of wrong association of material body being same as self.
What the suttas claims is that these material products are "not-self" and not that there is "no-self". I have analyzed some of these suttas at the below-marked blog:
Buddha & the concept of Anatta
(I welcome those who do not agree with my above analysis for discussion.)
Thus, from the Jain point of view, this approach of Buddha can be understood as an attempt to help disciples move out of all the wrong notions of equating body with self, so the understanding of the true self of 'Atman' may be achieved. The modus-operandi of achieving the right understanding of self may be different from the Jain perspective, but the essence is the same and thus we cannot denounce Buddha as propagating against the concept of 'Atman' or Soul.
2. Eating meat.
Vegetarianism is like the essence of Shramana's thought. As Buddha started administering His ministry, like every other Shramana master He too made vegetarianism a rule for His monks, till one day an eagle flying in the air accidentally dropped a loaf of meat in the begging bowl of one of His disciples.
This created a paradox. Buddha had made vegetarianism a rule, and another of not wasting anything that has been offered to them. Thus the monk went to Buddha to enquire what should he do with the food. This led Buddha into deep contemplation.
One of the fundamental principles of Shramana thought is to be logical and analytical in following its precepts. Vegetarianism should be no exception. The essence of the vegetarian lifestyle of Shamana's is compassion. It is to avoid any direct or indirect harm to any living form. Meat cannot be obtained without killing, and thus this school advocated a vegetarian lifestyle.
In this case, the meat was offered accidentally, without any intent by the monk, and thus with no influx (ashrav) of any resulting karma on the part of monk.
Thus, Buddha permitted the monk to eat meat as long as there is no direct or indirect attempt by monk to receive the same. Now the monks started accepting meat when offered to them. In fact, since many of the monks, including Buddha had been former Kshatriyas (warrior class) and thus meat-eaters, the lay followers, in hope of receiving more virtue by offering more liked-food of monks started offering more and more meat.
Buddha however realized that this meat-eating is going to further degrade in His tradition and thus in the Mahayana Mahaparinirvana Sutra, which presents itself as the final elucidatory and definitive Mahayana teachings of the Buddha on the very eve of his death, the Buddha states that "the eating of meat extinguishes the seed of Great Kindness", adding that all and every kind of meat and fish consumption (even of animals found already dead) is prohibited by Him. He specifically rejects the idea that monks who go out begging and receive meat from a donor should eat it: ". . . it should be rejected . . . I say that even meat, fish, game, dried hooves and scraps of meat leftover by others constitutes an infraction . . . I teach the harm arising from meat-eating."
The Buddha also predicts in this sutra that later monks will "hold spurious writings to be the authentic Dharma" and will concoct their own sutras and falsely claim that the Buddha allows the eating of meat, whereas he says he does not. A long passage in the Lankavatara Sutra shows the Buddha speaking out very forcefully against meat consumption and unequivocally in favor of vegetarianism, since the eating of the flesh of fellow sentient beings is said by him to be incompatible with the compassion that a Bodhisattva should strive to cultivate.
As predicted by the omniscient, today, Buddhism as we see has completely deviated from the fundamentals of Shramana school. The schools of Buddhism that advocate meat-eating claim that the suttas like above, promoting vegetarianism are faux.
Till the point, the monks were begging for alms, as was the case in the days of Buddha, the acceptance of meat may still somehow be justified as it did not lead to an influx of karmas, but the meat-eating that now takes place in residential monasteries where the meat is specifically purchased to feed monks certainly does and can in no way be approved by Buddha.
However, the question we are discussing here is not of Buddhism, but of Buddha and thus denouncing Him as promoting meat-eating by Jains is not appropriate. When seen through the prism of Shramana principal of Anekant-vaad (multiple points of view), the reasoning behind the circumstances He permitted can be understood.
Thus, from where I see, Buddha was completely in sync with the above fundamentals of Shramana principles of which the Jains often accuse Him to deviate.
2nd Section
Possibility of the existence of more than one enlightened master simultaneously.
Jains often claim that since Jina was the Tirthankara, Buddha was not equal to Him. Its worth understanding that as per Shramana theology, conceptually there is no difference between the enlightenment of a Tirthankara and that of an Arihanta. They both are equally enlightened with Keval-Gyan and are at the 13th stage of Spiritual existence (Guna-Sthana). They both merge back into Siddha after the material life is over and become One with Him.
The primary reason behind someone becoming a Tirthankara is that He in His past lives had performed such virtuous actions in promoting Shramana tradition that He has bound for Himself a karmic-bondage to be the blessed one. Thus its a product of the past karmic bondages of a person, and should not be regarded as the proof of someone being superior to another enlightened master in any sense.
Hope I was able to justify my above claim.
Criticism is most welcome.
Love