Nope...
It's all mW.
Green is the brightest.
Blue is the coolest looking
and I guess you can say red is good for burnning.
They say this because, red is the least brightness, so you don't need goggles when burnning (Well you do, but if you didn't, you could see what would be happning)
Blue use to be the highest amount, regardless of mW, but due to breakthrough in laser technology, we can say it's the cheapest.
Buy a laser from wicked lasers, I recommend the red pulsar, bye the wicked cap set, and laser goggles. That should be about 200 dollars.
If you have any spare, bye the case for it, and you got a nice laser that can cut tape, pop balloons, smoke leather...