Anecdotally from people I talk to, Android users tend to be of the techy male (less likely to share quotes and use self expression tools). Also it seems that the Android crowd is used to free a lot. When Rovio charged for the iOS version of Angry Birds but released the Android version for free, I'm sure they looked at the numbers when deciding what made the most sense for them. Also I think the Instagram crowd is still much stronger in iOS. I could be totally wrong.