Switch your light on momentarily to locate your target, move, turn the light on again and open fire if necessary. That's the "tactics" in "tactical."

That's why a tactical light will have a forward-clickie (allowing momentary-on operation), often a grip ring to facilitate a "cigar hold," and a button that protrudes from the rear of the light for easy operation (as well as remote pressure-switch options, e.g. for a shotgun). Weapon-mounting hardware, filters and diffusers may also be available for the specific light in question. If they're built to be weapon-mounted, they should also be able to handle recoil forces.

I imagine DealExtreme classifies any light as "tactical" if it has an assault bezel, of course