Unfortunately the terms that we are now discussing these LED lights have been set by the marketing and advertising people and, as usual, they are wrong. We really need to be discussing the LED on the basis of radiant flux or radiant flux/ Watt- not Watts. The Bridgelux NLX-5 and NLX-6 are not true 3W devices, but this is way it has been framed by the marketing people. The NLX-6 in the 60 mil package is at best a 2W device. You have to be very careful about reading the specifications of these LED's- if your cooling system is VERY good, you can perhaps exceed 1W of current injection through the device. Please read carefully the tech data stuffed at the back of the Bridgelux spec- Current Derating Curves. You must maintain exceptionally low Junction-to-Ambient resistance to run these dies at levels exceeding 1W. Anyone who thinks you are getting there with a chunk of aluminum and a fan is delusional.
Since we are looking at the Bridgelux spec sheet- you can clearly see the side view breakdown of the various layers on the chip. You can see Bridgelux is clearly a 'lateral' type device growing the GaN layers on a sapphire substrate. Thermal performance of sapphire is not good- it is not easy for the heat to beat it's way through the material to be released into ambient. This, and the lateral structure of the die itself, is the killer with these dies, but they are still much better than what you would typically expect to get from a Chinese vendor. Also, you can see the LG ad listed a whole bunch of wavelengths which are clearly NOT available from Bridgelux.
So again- what is the difference between a lateral die on sapphire vs. a vertical die like Cree- again, a lot in terms of efficiency. You put more power in but get less light out. In addition- when run at high current levels/ temperatures, this destroys the L70/ 50 lifetime characteristics- these fixtures are not going to last the claimed 50,000 hours. Of note, we regularly get Cree EZ900 blue dies at guaranteed radiant flux levels of 340mW minimum pulling from the variety of bins that all the die manufacturers make you pull from when you buy these devices- no, you can't just pick the highest power bin and pull from that one. Only a very small number of dies coming off the wafer will fall into the highest power bin. Perhaps when Bridgelux perfects their silicon epitaxy process thermal management for these dies will be somewhat easier.
I think many of the fixtures coming out of China are actually made of small LED arrays comprised of half a dozen or so small chips that they are claiming are 2 or 3W 'LED's'- I guess they can say whatever they want, however these will be very inefficient and the lifetime is in question. For the record I am not a salesman and I do not produce horticultural lights. I do some work in LED architectural lighting, street lighting, and automotive- I am not here to sell anything or promote any product of any kind- just trying to help de-mystify this LED stuff for anyone that is really interested in learning about this technology.