The SC Nouveau features Yamaha's Nouveau lug system, where as the regular SCA does not. The Nouveau system allows head changes without completely removing the tension rods, all you do is loosen them, and then you can pop the rim off at the "nodal point" where the lug joins the shell. It's a heck of a time-saver, and very handy.
If you have any other questions, don't be afraid to ask. I run a Yamaha group on Yahoo for drummers who play Yamaha acoustic drums. Among our members are Yamaha endorsers Erik Smith and Dave Mattacks, and Yamaha USA Product Manager Jim Haler. It's free to join, all you need is a Yahoo ID. You can find the group here, hope to see you there if you are interested: