UMP is a smg that use 9mm ammo type. UMP has low recoil and with the help of some attachments UMP will has even less recoil when it equip. Using UMP for pushing compund or holding enemy position is really good because of it fast bullet projectile and for early landing against no vest enemies target.
Uzi is a type of smg that use 9mm ammo type. Uzi can't attach scope. Uzi is the perfect early game rifle to use because of the insanely fast bullet projectile and also accurate in close range. For Early landing if you know that enemies are near you and you found uzi you better rush them.
Vector is a sub machine gun that use .45acp ammo type. Vector bullet projectile is really fast and with .45 acp bullet it can kill enemies with vest within 2 seconds if they hit all the shots. Vector is a very good smg to use for mid game because enemies won't expect how fast they could be killed in close range.
Tommy gun is a type of smg that use .45acp ammo types. Tommy gun can't attach any scope. Bullet projectile is lower then Vector but is dose better damage. With the shortage of sight the is hard for long range and it's only prefer to close range.