The nexus uses a micro-sim card (smaller) so you will have to go to Verizon for a new Sim. As far as differences, android is android, you just have to get use to the little differences like the menu button being 3 dots located in different spots on the screen. Oh and we just got jelly bean, my old bionic was still waiting on ICS. Guessing that hasn't changed.
Well I don't mean differences android wise, I already have it on the OTA jelly bean and I rooted and put a rom on it. I'm just wondering with the having a new sim card with it can I switch back and forth from Bionic to Nexus or do I have to go in each time to reactivate the sim card?