As a rule of thumb, the NTSC-U/C version is the original game, released in North America (U/C stands for USA/Canada). It's named after the analog television standard used in this region. The PAL version is the same deal, but it's used primarily in Europe and Australia. It has a larger screen resolution at the cost of a a lower frame rate. Japan uses its own variant called NTSC-J, which is mostly similar to NTSC-U/C in terms of screen display.
Because the PAL and NTSC-J versions of most Crash games were released some time after the original NTSC-U/C versions, they often feature many differences and updates, ranging from localization to bug fixes, as well as a few additional features here and there. Despite that, the NTSC-J versions of the original PlayStation games were based off of NTSC-U/C, so most of the PAL changes weren't carried over to them.