Originally Posted by
wyeast
Particularly with 5mm leds, it's pretty easy to compare based on numbers of emitters. Once you start getting into more powerful Luxeon, Seoul, and Cree emitters it starts getting goofy with efficiencies.
One difference is that in the past few years Nichia came out with higher efficiency 5mm LED's, which boosted their brightness. But in general you're looking at apples vs apples.
Without ripping a light apart to see whats inside it, the best indicator of brightness is battery type and runtime. A 100hr light will be a third the brightness of a 30hr light(of course this goes out the window with flashing lights).