I think the main difference was textures: on the 64 they ended up being blurrier/flatter and therefore less pixelated. That said, there were definitely PS1 game

I think the main difference was textures: on the 64 they ended up being blurrier/flatter and therefore less pixelated. That said, there were definitely PS1 games that looked great and weren't cursed with jaggies (Wipeout, for instance).