Based solely on what I’ve seen and read (note!) about Android’s upcoming tablet-centric Honeycomb release, and my experience with Android on my smartphone, I think the difference between Android and iOS is quite clear.
Android is looking to bring desktop computing to smaller, newer form factors. iOS is looking to redefine computing for smaller, newer form factors.
I don’t see Android destroying any desktop paradigms, offhand. It may take some ideas from iOS and improve them (notifications look to be way better.) It is definitely taking desktop ideas and changing them. But even the fact that there’s a dashboard/home screen which has widgets that are user-configurable shows the difference: you need to devote time to customizing an Android device to make it work the way you want.
This is a trade-off which many people are fine with and, in fact, may tout as a great thing. For me, though, the value of not having to fully customize and configure a system is a large one - and, I suspect, it’s true of many people who haven’t historically been computer users.