The main differences are that the larger engine has more torque and will pull better. However in many localities the 48 cc is legal while the "80" cc isn't. Most people count on the fact that the cops can't tell the difference. I suspect that the law won't stay stupid forever so I run the 48 cc just in case. It is fast enough for me anyway.
If it can't be broken I'll find a way!
I'm not lost, I'm exploring!