Honestly, I don't think it matters. It's not enough to make a difference in a meaningful way (Well, the longer barrel of the newer one would give a greater muzzle velocity, but semantics).
Look at the to top. The Original also is shorter
Still want to know which is the Canon MA5B. The Halo Wars/ Halo: CE version or the Halo: CE Anniversary versionWell, you could always make the argument that the CE one is simply an extended magazine, and that they are all the same minus artistic integrity. They look pretty similar to me, minus the CEA one being a lot less bulky.
As stated in canon fodder, new graphics trump old ones. Like it or not (though I think Mombasa can be an exception ,as ODST is a much more detailed variant of the city that makes a lot more sense than H2A). So the current Ma5B from CEA that more resembles the MA5C and MA5D is the 'canon' appearance.
HOWEVER, the M45T/ M90 shotgun difference was settled in the the data drops, wit ha ntoe from Silva to Keyes saying he's getting sick of Autumn's complement of spatans geting first choice of weaponry. You could easily argue both the original and new are the same variant of MA5B, but have minor differences comparable to the M16A1, M16A2 and so forth. Or that the version from CEA is an MA5C rifle. There's a lot of ways to justify it using headcanons, because I don't really think that it is something so important as to warrant unnecessary attention.
If you can't see a difference between the MA5B
and the MA5C.
Then I don't know. Look at them side by side. Also the look between the MA37
(Called the MA5 by Marine and Naval forces) compared to all of the other MA5 systems. Looks completely different then any of the other systems. Even the MA5D
saw improvement in design and performance
There is a difference between the M16A1 and the M16A2 in looks. But they proform differently. The A2 fixed a lot of issues that caused the A1 to jam in Vietnam and was more accurate. Also the Full auto was replaced by burst. The A3 is exactly the same as the A2, but the Burst was Replaced by Full Auto. The A4 saw the greatest change with an improved performance and adjustable butt stock and rail system all along the upper receiver