If you've played both games I shouldn't really need to. But anyway:
24 car races
Fairly intelligent AI (Not the best, but miles better than GT5)
19 real world tracks to race on
Dynamic weather on EVERY track
Pit stops/strategy
Full damage (albeit not sensitive enough)
Proper flags/penalty system
Full seasons or individual races
GT5 might be better in other aspects but in terms of racing F1 2010 was much better than GT5 for me.