What are the differences between Indy Cars and Formula 1?

May be...

Indy Cars use all use the same chassis and Honda engines
F1 cars use team built chassis and different engines makers(Mercedes,BMW,Ferrari,Renault,etc)...
Sorry, but that's about all I know, aside from Indy Cars running ovals as well as road/street courses, and F1 cars running only road/street courses.

http://www.indymotorspeedway.com/vstech....

Like power, engine types, big rule differences etc?

How do they compare for top speeds?

F1's are heaps faster than Indy Cars.Indy Cars use the same things where as F1 use all deferent tyres,chasis,gear boxes and dofferent motors.dig dug commercial