LED Specs..

[Lampshade]

The difference with an LED 6500 bulb and a noramal T5/MH bulb is that an LED 6500 is peaked very much in that range, with very little spread into other spectrums. A regular 6500 bulb will cover all spectrum's around that area, including lots of red, which is great for algae growth. Cree spec sheets show the spectrum of the bulbs, they're very close to what our corals need, without too much wasted(except for lots of yellow). The blue's are peaked at the high absorbent range of most corals, so it helps out a lot in growth.

Here's some sites:
RC thread on coral spectrum - http://www.reefcentral.com/forums/sh....php?t=1496092
Cree XP-G sheet - http://www.cree.com/products/pdf/xlampxp-g.pdf
Sanja;ys lighting guide(to compare a 6500 MH bulb if you want) - http://www.manhattanreefs.com/lighting