As for that heat management test, it's designed to see how each bulb performs as it heats up during use. Just like the way your laptop can slow down when it gets too hot, LEDs will see a slight drop-off in brightness in the first 30 minutes or so of usage as they heat up -- by that point, their heat sinks should kick in and stabilize things. 

Bulbs that finish higher are losing less of their brightness during their initial dip and doing a better job of keeping heat at bay. Good heat management leads to better efficiency, because it lets the bulbs put out more light from the same, low power draw. A bulb that's good at keeping the heat at bay might be a smart pick for an enclosed fixture, where heat tends to get trapped.