Wikipedia seems to do a good general job of explaining fluorescent light bulb technology at http://en.wikipedia.org/wiki/Fluorescent_lamp Lots of technology hidden in a fluorescent bulb! But I did not see any explanation of how, say, a 13 watt compact fluorescent lamp (CFL) differs from an 18 watt...or for a full sized fluorescent,either... It looks like the two basic components affecting light output are the gas and a fluorescent coating inside the bulb...but what is done to get more or less light from a given physical sized bulb?? Are both components varied or one or the other??