Very generally, in my opinion:
Bloc = more bouldering than climbing, newer than R& R, closer to Mt. Lemmon, more expensive housing.
R&R = more climbing than bouldering, near downtown, less expensive housing, more university students at night during the school year.
Both are owned by same person.
Setters move back in forth between both gyms and there are some very good setters.
I believe a general membership is good for both gyms these days.
The one that is better--- is the one you like better.
Welcome. Hope you enjoy Tucson.