Its because they have a case enough to fit in all the red itemin terms of space so sometimes they just bring the bare minimum to rush safes or pvp then just case everything valuable and because they are pvp chads they will just get the backpack of the enemy they kill which is almost always the 926 backpack or field
H4 doesn't have the trigger bolt, if that's what it's called, on the right, making it fire a little faster than m4. Also more streamlined for ergo as well