It's not just the difference in app numbers, in app quality, in app language (you can probably do more with 1gb of memory in objc than java), but it's the integration, the user experience. On the computer, it's all well and good doing everything on your browser, but unless you're in full screen mode you're seeing something other than the page you're on. Apple does that bit best. (and others, but it's further ahead in the look of the out-of-app bits)