Those are the same LED, but different bin designation - meaning that mine are from the group of that part number which have a lower lumen output, the Q2 bin vs the Q5 bin. Mine will be about 87-94 lumen vs about 107-114 for the Q5, at 350 mA current. As I understand it, a given production run of LEDs will have a wide variation in efficiencies, so they isolate them by the range of outputs, and "bin" them with similiar output ones. There are other differences too, in color temperature, for example, that result in a given LED being in a different bin.
Also, the LED "emitter" can be mounted on a "star" circuit board by different distributers, and I think the ones I'm getting are mounted by DealExtreme.