just to illustrate the difference between the banned AR-15 vs. the legal Mini-14 (both rifles are .223 and semi-automatic) i've included these pictures:
banned:
legal:
Keep in mind, that both of these guns are the same caliber, and both are semi-automatic (one pull of the trigger and the gun fires one time), the biggest difference between these two weapons is simply that one looks more menacing than the other. Both are just as deadly, and to be truthful, I ran across somebody hunting a couple of years ago w/ a pre-ban AR-15 (imagine that, somebody hunting with an "assault weapon" )