Actually- there are differences other than the peban type features.
An obvious difference is the buffer.
LE and military come with a metal buffer, most regular civvy ones came with a plastic buffer.
This may have changed recently with the new Colt post ban M4. The ones I saw had metal buffers.
Another difference is the FA cutout in the receiver.
Colt also is now making its rifles with two push pins. The LE ones sometimes came this way, sometimes they didn't. No rhyme or reason I know of. Same with the pin diameters. "Floor sweepings" maybe.
The majority of parts are the exact same as the military version and, as far as I know, the parts similarity between them is increasing.
But, as I stated, the differences were internal and the pre ban features.
Hope this helps-Mike