Over the last few years Colt has been changing the cosmetic features of the 6920.
The 6920's of years ago had the Colt large diameter hammer and trigger pins, and the original type CAR-15 Fiberlite collapsing stock, and a semi-auto type bolt carrier.
These were stamped as AR-15 Carbines and had standard type carbine barrels.
The 6920 of a few years ago went back to the original size pins, changed to the current M4 collapsing stock, changed to the M4 profile barrel, changed the stamp to "Colt M4", changed to the full-auto type bolt carrier, the large oval shaped M4 handguards, came with 2 20 round aluminum magazines and the carry handle/rear sight.
The 6920 of the last few years was the same only it had the Rodgers/Colt Super Stock collapsing stock, 2 Mag-Pul 30 round magazines, deleted the the carry handle/sight and changed to the Mag-Pul BUIS folding rear sight.
The 6920 of this year went back to the M4 collapsing stock, still has the Mag-Pul BUIS folding rear sight, has only one Mag-Pul 30 round magazine, no cleaning kit, and no sling.
This is from memory and I could have some of the older carbine features wrong.