The M4 is basically a carbine version of the M16A2 rifle, and was developed both to reflect the development of the M16A2 over the previous M16A1, and to correct deficiencies which had been identified with the XM-177 (which was the carbine variant of the M16A1).
General differences between the M4 and M16 include:
Some people often cite the removable carry handle of the M4 as one difference, but the first production run of M4 carbines had the same fixed carry handle as the M16A2 (I was actually issued one when I was in the FL National Guard).
M4 is the carbine- shorter barrel
The M4 CARBINE IS BETTER THAN THE M16.
Yes. Principle differences between the M16 and M4 include: M16 has a 20 inch barrel while the M4 has 14.5 inch barrel, M16 has a fixed buttstock while the M4 has a retractable six-position buttstock. Virtually all M4s have a 20 millimeter accessory rail, while only M16s after the A3 variant have the rail. The M4 carbine also has a stepdown in the barrel to accommodate the M203 grenade launcher due to its thicker barrel profile. Performance-wise, the M4 is also less accurate at range due to its shorter barrel, but is easier to maneuver in cramped environments.
The M4 is the carbine version of the M16 (carbine means short barreled rifle). Search Wikipedia for M16 for more reading.
Couple reasons, one being doctrinal differences between units. Another reason being is that some of the M16 rifles are special purpose weapons, intended for unit sharpshooters and the like.
Not really too much to tell. The M16 has a longer barrel, and the projectiles will leave the barrel with greater velocity for it. The M4 has the collapsible buttstock and 14.5 inch barrel, so it would be the easier of the two to utilise in urban terrain and such. The M16's longer gas system is the more reliable of the two, and the muzzle flash and noise of the M16 is reduced. The operating mechanism is the exact same, except that the M4 and M16 won't use the same return spring or buffer.
The M16 assault rifle has a greater range than the M4 carbine as a result of its 20-inch barrel, compared with 14.5 for the M4. The M16 can hit an area target out to 800 meters while the M4 is effective to 600 meters.
An M4 is a short barreled version of the M16, so yes, they can look quite similar.
The M16. The M16 entered production in 1960. The M4 entered production in 1984, and was an improvement over the earlier XM-177 carbines.
Yes, along with the carbine version of the M16, the M4.
Not entirely. The Marines retained the M16, and most Army mech units opted for the M16A4 rather than the M4.
The M16 and the M4 are the US designations for the AR-15 pattern of rifles.