[pearjuice]

Due to the ease of iTunes, Apple users have it way easier in having directly usable credit for the App Store. Besides, they already paid premium for their devices so it is likely they have additional money which they will spend on third-party applications for the iOS platform. Android still has this "It is cheap and free" imago so they are not heavy spenders and will not grab their wallet fast.

I don't have any data at hand to directly back this up, but my guess is it will be roughly like this. It would be valuable to have a report on how the high-end pricey smartphone owners (HTC One, Galaxy S4 etc) are spending more or less than the budget Android devices.