What is the difference between the M4 Carbine M4A1 and CAR 15?

Answer 1

CAR-15 is a commercial marketing name coined by Colt. The original CAR-15s were simply shortened versions of the M16A1, and tended to be a bit problematic. The M4 was a revamped version of the CAR-15 models ordered by the US Military (namely, the XM177). The receivers were based on the M16A2, rather than the earlier M16A1 receivers, extended feed ramps were added to reduce failure to feed stoppages, a 14.5 inch barrel with a standard flash suppressor was chosen in place of the 10 inch barrel and long flash suppressor used by the XM177, and there were some other improvements. Being designed in conjunction with the M16A2, the M4 has the same three round burst limitation as the M16A2. The M4A1 is more the same as the regular M4, except it is capable of true full auto fire.