They're completely different. I would imagine that if the same ride were in both parks, the name would also be the same.
California Screamin' is outdoors and uses a hill to gain momentum. Rockin' Rollercoaster is indoors and uses a magnetic launch system to go from 0-60mph in 2.8 seconds. CS also features only one inversion while RNR features one loop, two corkscrews and a g-turn.
Completely different rides.
And from reading the specs, RNR seems like a better ride.