It looks cool, it sounds cool, but it's not full auto. You can't shoulder the weapon properly or be as accurate. I'm not trying to be pedantic about this, but honestly, the biggest difference is that you can be more accurate with a real selective fire weapon. However the government doesn't know how to legislate common sense, and this is where we are at.
I wish I could say we have honest full auto available to all citizens who have no felonious histories, mental defects, or other disqualifying conditions, but I can't. Full auto is only for those with enough money to pay the artificially inflated prices.