I might have some photos of said colas but I don't think they turned out too well... my camera is crappy and I wasn't shooting to show the contrast.
The difference is huge. The first time I smoked one of those frosted nugs I almost freaked out because it was so unexpectedly intense... off one hit.
The light needs to be pretty close to the plants, 4ft away isn't going to cut it. It was usually 1-2ft from mine. There never was any sign of injury so maybe it could've been closer.
Just be careful with your eyes around those things. One time I entered the tent with it still on, and glanced at it - saw it glowing (it does produce some visible light), thought OH SHIT and went staggering backwards frantically escaping the tent... the rest of the night my eyes were bloodshot, dry, my vision was fuzzy... not good. So what I do now is turn the light on manually only, and when I do so, I tie a red bandana around the zippers, so I have a reminder. Do remember also, fluoros take a minute to stop producing light, and the UVB bulbs are fluoros, so... wait a minute to enter after you turn them off.