If you consider the fact the M16 was actually developed and made by armour lite you are really splitting hairs if you think there is much difference between an AR-15 and a M-16 carbine . ( or whatever it is called now).
I'm aware that the original M16A1 was manufactured by ArmaLite. That doesn't change the fact that the AR family is a civilian variant (i.e. A derivative design) that was sold in Sears catalogs nearly sixty years ago.
It's not splitting hairs to differentiate civilian variants from their military cousins. Confusion on that point can land you in prison for a very, very long time here.
Ownership of an actual assault rife in the U.S. requires a Class III firearms license, permission of your local police department and an extensive background check.