Washer method help us to find the volume of a solid of revolution of a solid state material. It helps a user to integrate along axis "parallel" to the axis of revolution.

On the other hand disc method is similar to how an egg slicer works. The disc method divides a solid into insignificantly thin discs using mathematics to find the area of large body.

As these are complex calculations in the concept of integration. So I would also recommend you using disc integration calculator & washers method calculator because it’s easy to use and help out for finding and understanding these concepts.