honestly, guys, how much variation do you expect? They mostly use AAs, CR123As, 18650s, or li-ion equivalents of the first two, since those are the available batteries. And they mostly use CREE Q5 because that is the most efficient available LED. The tail switch has become a standard. So what is there to change? I've only seen one flashlight that looks nothing like others taking its batteries, and that was the spy :)
and just as a comment - if a company creates several brand names for different product categories, they usually tell you. Like nitecore and raidfire - they even have a parent company name, edgetac.
Yes, eagletac's p10c2 does compete directly with fenix's t10. But I think that it is a matter of improving traits left undeveloped in the t10, not trying to copy them. Personally I can understand this, as I agree with eagletac that this is probably the best interface for a true "tactical" flashlight.