There are three flashbang-like grenades in Planetside 2: heavy assault troopers get a concussion grenade, light assaults use flash grenades, and infiltrators can carry EMP grenades.
They all have a similar purpose: disable hostiles, making it easier for your squad to sweep the area and making return fire more difficult.
But they seem to have different effects. What other differences are there? What is their effect radius? Is there effect reduced at further range? Is there some indication that a target is affected by such a grenade? Basically, I'd like a fairly in-depth description of all these devices.