The (U) and (J) versions run at 60Hz (30 FPS) , whereas the European (E) or PAL versions run at 50Hz (25 FPS) . This makes the North American version feel significantly faster and more responsive.
The in a filename stands for the North American (USA) version of the game. For most players, this is considered the "standard" version for a few key reasons: mario kart 64 u z64 better
Often used for files dumped by early PC-based devices. It’s technically the most "unnatural" for the original hardware. Which one is actually better? The (U) and (J) versions run at 60Hz