I read somewhere (Don't ask me where.....) that a canine - Fox, coyote, dog, etc. doesn't have a certain cone in their eye that can detect red and green. For lack of better words, they are sorta color blind. That's the theory behind using red and green lights....the canine's can't detect it and therefore they don't scare away. Personally, I'm not sure I buy into that theory. They may not detect color, but they can probably detect the brightness the light is putting out. I can close my eyes, but when you shine a light in my face (even with my eyes closed) , I know there is a light shining on my face.
As Bowman66 (Darin) stated above, a shoot light is mounted on a gun usually and used when closing the deal. The beam is usually more pinpoint and focused. A scan light has a wider "halo" and not as pinpoint and direct. Think of it this way.... A shoot light is like a spot light, and a scan light is more like a flood light.