Most of those are pistols, which is a separate part of kit. The end of that list shows the M4 carbine - which is an AR-15. In popular vernacular, an “M4” is a

Most of those are pistols, which is a separate part of kit. The end of that list shows the M4 carbine - which is an AR-15. In popular vernacular, an “M4” is a shortened version of the “M16”, which is the military version of the “AR-15”. Armalite originated the design and Colt licensed it. There’s a bit more to it than that, but that’s the high points.