M4 or ar15
 

My rifle has M4 Carbine stamped on it is there a difference in a ar15 and a m4 and if so what? I took a pic so you could see what I mean. The serial number also
Starts with LEO.

Attachment 37590

its just a model name. a true m4 carbine is select fire with a 14.5" barrel as its two most distinguishing features.

colt has marked a couple of models of their civilian and law guns with 16" barrels and semi only with M4 for a while. its still an ar15.

Are they technically a "CAR-15", or is that different as well?

I refer to mine as an M4, but just because its an M4 style carbine and has the 14.5" barrel,semi auto of course. Mine is a Stag...model stag-15 5.56 Nato

typically "car" just refers to a carbine length gas tube and 16inch barrel. but the actual original CAR designation stands for colt automatic rifle which was the xm-177 full auto with 11.5" barrel.

I had always wondered about that...thanks!

tenntyrant, JonM's answer is dead on - as it is you have an AR-15 modeled after the military M4. Your Colt is very, very close to being a true select fire M4 and if it were legal you could get it even closer by shortening the barrel to 14.5" and buying a select fire lower receiver. Of course it would be insane to consider such a thing, just pointing out differences.

Often AR-15s modeled after the M4 are called "M4geries" to distinguish between the real thing. Close, but Uncle Sam won't give you the cigar. :D