Looking at getting a new upper for one of the carbeans (I prefer Colt - I drink the Kool Aid)

Was thinking just the standard 14.5-inch M4 (6921) barrel, but seem to be seeing a lot of the heavier M4 SOCOM barrels out there too and had a couple questions...

What (if any) advantage is there with the heavier SOCOM barrel?

What is the difference in weight between the two barrels (I'd be building up the upper the same either way, so the only real difference is going to be the barrel).

Thanks.