This was posted in another section on the forum but will address your concerns.
To quote the article
Now according to this compilation of MilSpec with the Sloyer's data comparing commercial M4s component-by-component, Colt's 6920 is the only commercial AR-style rifle that hits all of the key indicators for military standards. What does this mean? Nothing really, only that the military's main supplier of MilSpec rifles is following all of the military standards for their
I like the fact that my 6920 says "M4" on the lower. It also says 1/7 on the barrel.
Not really saying it is better in any way than my S&W, but it is nice to own a Colt.