MUZZLE BREAKS- use the gasses escaping from the end of the barrel to help buffer the recoil. Some of the gasses are redirected in order to lessen the recoil. Most often seen on field peices or tank guns.
SUPPRESSORS- Kind of a miss nomer. By allowing most of the gas to escape in controlled direction it limits to flash observered by the shooter. If you look at a flash supresseor, it doesn't have any slots at the top. This causes the flash to be dirrected down, helping the shooter to observe fall of shot. Most often seen on small arms.
COMPENSATORS- Not sure. Not a term I'm familiar with. Anyone else?
SILENCERS- Chambers inside the silencer help muffle the sound of the shot. Does reduce the sound significantly, but no, not like in the movies. Most often on small caliber and slower projectiles. 9mm for example.
Those Who Live By The Sword Will Be Vaporised With 105mm HESH By Those Of Us Who Have Progressed