What is the difference between the two sides of a nail file?

Generally one side is a rougher file grade, used for initially shaping the nail, removing rough edges, if the nail broke at a funny angle, you can use this side to smooth it out a bit. The finer grade/side it used for a more precise shaping of your nail. use it to smooth out the edges of your nail, and create a better shape.

You can also buy nail files with more than two sides. These are called buffers and are generally used for the actual surface of your nail to provide a high shine without using nail polish.

Always remember when you are fileing your nails to use long smooth movements in one direction as opposed to a quick back and forth sawing motion. This prevents the nail from splitting and causing more damage than you already have.

Are you sure both sides are a file? It really depends. Some come with two sides exactly the same, both for filing. Others come with one side for filing, one for buffing. The buffer is used differently, on the tops of your nails for shine. If it's a metal file, both sides are likely the same. If it's made of anything else, and one is smooth, that one is likely a buffer while the rough side is for filing.

I don't know if you are trying to trick us here. If you have a nail file it's obviously visible what's the difference. Since I'm a hundred percent you've used one yourself you know the answer to your question. But if you're pulling some tricks, I would say 1/8 of an inch. That's the approximate thickness difference between two sides.

depends on the file. for some of them one sides more abrasive for heavier duty work, while the other is more for detailing. on most though it's just once you wear out one side you use the other, there's no difference

one side shapes it better while the other side is a finisher and make it smoother