The part that's relevant to most of us is that while Google Play is poised to surpass iTunes in catalog size, it brings in 1/4 the revenue.
Not the sort of stat that puts a smile on my face.
You're comparing apples and oranges. The Apple app store and the Google Play store will never have a vaild comparison for revenue generated, because some decisions are not up to neither Apple nor Google. An earlier post mentionned how Rovio and EA were overrepresented in the top sellers, and they are probably responsible for most of the revenue generated in the Apple app store. Heck, just Angry Birds, including all its remakes, probably makes a significant share of that revenue.
Rovio is itself responsible for a huge part of the difference between the revenues on Apple app store and Google Play. Why? Angry Birds, priced at $0.99 on the Apple app store, is free on Google Play. The exact same game, being downloaded millions upon millions of times on both platforms, generate infinitely more revenue on the Apple app store for the simple reason that they're giving away the game for free on Google Play.
They probably have good reasons to do that. They might have considered that people on Android are cheapstakes and wouldn't pay a dollar for a game and they prefer to be ad-based. Or maybe they figured they'd make more from in-game ads on Android than with an ad-free purchase, while on iOS the game is different. Either way, we can't compare $$$ from the Apple app store and Google Play, because they are not the same, and often times, the same company will sell the same game very differently on both stores.