Google Play: 10 times the amount of downloads than Apple Store
Apple Store: 2.5 times the income of Google Play.
Reviews on Google Play frequently mention how everything should be unlocked for free. Apple reviews seem to focus more on what extra content they would like to see.
Piracy on my paid apps seemed to be way, way higher on Android.
Since kids tend to have more time than money, I'd also expect games/apps they use to have a higher degree of piracy, at least when it is relatively easy.