(summarizing results of a quick google search)
For the SNES specifically, the physical connector is identical, and most of the pins are also the same.
However, pin 3 supplies CSYNC on early NTSC SNES models (disconnected on later ones), while PAL consoles supply 12V (!)
tl;dr Composite and S-Video cables are identical between regions, but RGB cables are region-specific so you don't damage your equipment.