The Japanese NTSC is based on the U. S. except its a bit more "modernize".
The U. S. NTSC still haven\'t changed some of the things yet like:
they still uses 7.5 IRE for black level whereas Japan had had switch to 0 IRE for black from a scale of 0 - 100 IRE. Where 100 IRE is completely white.
The color gamut, not sure if U. S. had modernized the color gamut with the color temperature of 6500k and color decoder yet, but I believed Japan had.
besides that, both have the same resolution of E. I. A. 525 lines interlaced (about 480 lines active) of 60 Hz.
PAL, although uses higher resolution, about 600ish and about 576 active interlaced lines of 50 Hz. I think PAL had the accurate 0 - 100 IRE of black and white level long time ago and their color temperature is 6500k and their color gamut is pretty darn close to what HDTV uses for color gamut.
So, to sum it up, PAL have a higher resolution while NTSC have refresh rate. Which is better? The better question is, which do you prefer? I prefer NTSC 60 Hz over PAL higher resolution.