Thats pretty much what they all are,and some can serve as both flash hider and break. I honestly cant answer the visual difference that set the two apart, but it may be partially due to the different hole and slotted patterns that are used to which job it will do. I use a smith enterprise Vortex flash hider on my M4 and it also acts as a partial muzzle break. Another good one to look at is the AAC Blackout flash hider.Both of the companies that i have mentioned also make a DC "direct connect" sound suppressor that attaches over the flash hiders,if you ever wanted to go that route.
Semper paratus.....virtute et armis