The front wheels are different. The America has a smaller diameter, but wider tire/wheel. The Spedmaster has a taller, but narrower tire/wheel.
The handlebars/risers have changed on the Speedmaster for 2011+ model years, as have the seat.
I like the direct feel with the drag style handlebars on my Speedy, however, they don't work for everyone. Rivco makes alternate risers. My wife and I have the stock setup, and they work well for us.
2010 Speedmaster Black w/ New England White. Air Injection Removed. TTP Breathe, TTP O2 Sensor Kit, TTP Tune 2, DNA Air Filter, Trident Exhaust.