NTSC has different F1 cars (6 or 8 I think) compared to the PAL version which has two : the polyphony 001 and 002. The soundtracks are different too, and the NTSC version has a lambo and the PAL version hasn't
There's a couple of extra hidden cars as far as I know [in NTSC]...
Plus the prize cars are different from winning competitions I think, and the speed is in mph [NTSC] and kmh [PAL].
Finally some of the times for licences are different...
All I can think of.
NTSC only has 2 licence test that require a faster time for gold than the PAL version, R5 and R6 i think, biggest difference ive found is S8, 1:27.000 for gold for the PAL users and 1:31.000 for NTSC
heaps but there is only the 2 in which the NTSC guys have to run a faster time
every other test they do is the same time or slower (guess some of them cant drive that fast ) that should get a bite or 2