Yes, on the RB's you have to cock the shutter separate from advancing the film.
On RZ's when you advance the film it cocks the shutter. The disadvantage of the RZ it that it's a little more expensive and relies on batteries for the shutter. Another advantage is that you can use both RZ and RB lenses on the RZ67 camera but you still need to cock the shutter when using the RB lenses.
I used to own an RZ67. In my opinion it is the best medium format film camera for portraiture out there. If you buy one make sure you get the 110mm lens with it. It's fantastic!
I have also owned Bronica Etrsi, S2a, EC, Pentax 645, 645N, 645Nll, and Hasselblad 500c/m.
I sold my RZ to help fund my large format cameras. I am not a pro but I do enjoy portraiture.