The RR's were always fuel injected (they took the injection system directly from MotoGP) it also has better rear suspension. The RR means Race Replica, it has a more aggressive (less comfortable) seating position (think racebike

)
the F4i is less aggressive/more comfortable with a broader powerband
Either one is certainly fast enough to make you shit your pants if you're hard on the throttle (110 HP vs 118 and they both weigh ~370lbs). Theres not much benefit to having the RR over the F4i aside from cool factor unless your last name is Rossi