Difference between a Compensator and a Flash Hider???

[supra95tt]

What is the difference between a compensator and a flash hider. I was told by someone that my AMD-65 muzzle break was a "Flash Hider" and is illegal on an AK-47 and I would have to change it (FYI I had to add the AMD-65 break to one of my AK's due to the length requirements - ^30"). I always though that the compensator grooves ran radially along the break and the flash hiders ran axially. However on the AMD-65 and my AR-15 the muzzle break grooves run axially. Can someone clarify this. Thanks in advance. BTW - I hope I posted this in the right section since it is a build related thread.

[ar15barrels]

According to most readings of the state law, anything that reduces visible flash is considered a flash suppressor for legal reasons.
A flash hider is different than a flash suppressor, but a flash hider is also considered a flash suppressor as it reduces flash too.
The feds go by what the manufacturer calls it, but the state goes by how it functions.

Now from a design perspective, flash hiders generally have open fronts to allow lots of air to be drawn in from the sides to extinguish the flame.
Muzzle brakes usually have small diameter exit holes in front to force all the gasses and flames out the side which recuces recoil and muzzle jump.

Based on the way the state interprets their laws, a manufacturer can put a flash suppressor in a package that says it's a muzzle brake and it's still a flash suppressor.
Based on the way the feds interpret their laws, a manufacturer can put a flash suppressor in a package that says it's only a muzzle brake, the feds would not consider it a flash suppressor.