Fail zero parts kit question

Hello all,

I was just poking around the fail zero web page. I noticed that they offered ar-15 parts kits and also M-16/4 parts kits. these kits start with the BCG, and a hammer, them progress to adding a stripped upper.

My question is not with the fail zero products. My question is with the AR parts kit versus the m-16 parts kit. Are these items not the same for both (essentially the same) weapons? If they differ, what does the official m4 or m-16 have over the AR?
Minus the fire control group, obviously... wait, did I just answer my own question?

please help me become more knowledgeable:)

The AR-15 is the Semi-Auto version while the M16 is the Full-Auto.
They're only different in that the M16 version has less metal removed on the underside so it can trip an auto sear. Just do a google search for full auto bolt carrier and you'll see.