Bit different philosophy. Wine does everything by the book to ensure maximum compatibility both now and in the future, even if it costs performance. Proton does per game dirty fixes, which requires more maintenence, but game with these fixes work better.

I don’t have hard numbers, but my understanding is that in general, Proton is more receptive to hacks which get stuff working, or working faster, but that aren’t proper solutions. WINE has a greater preference toward correctness, so compatibility is a bit worse, as is performance.