Know what the difference is? Nothing. One is a AR-15 the other is a .223, but they both fire the same ammo, both can be semi-automatic and both can get extended clips. The only difference is the look, unless you have a class 3 license or military clearance to get the full-auto version.
The AR-15 is basically a "range princess" for weekend warriors who enjoy the military aesthetic. Why someone would buy that version over the hunting one for their kid I have no clue. My 10 year old niece is getting a youth model .223 for Christmas to go hunting with her dad. It's a weak gun imo.