Whats the differences between these Motorsports?

[Redline]

I know what some of these are, but what are the rules, differences between them? Feel free to throw out different motorsports that I have missed.


CART?
F1?
Indy?
Lemans?

[Bobbeh]

Too many to list :) You'd talking engines, tyres, aerodynamics, fuel, driver numbers, race duration, track types etc etc.