Welcome to the site, John. Just call it a Bonneville to the insurance companies. You're not being deceitful or committing fraud, if they ask which one, then modify it with America or Speedmaster. You could always move to Florida, motorcycles aren't required to have insurance as long as you wear a helmet.
As for the differences between the two:
The Speedmaster stops harder.
The America's bars sit you up nice and straight and are closer to you.
The Speedy's bars sit lower and stretch you forward, better at higher speeds.
