First of all, the two operating systems just have different requirements. For example, Android requires that your menu bar be along the top, but with iOS we have placed it along the bottom. So various structural differences are there simply because the different systems require it that way.
Since Android is an operating system which runs on more than 8400 distinct devices it's nearly impossible to create images that will look perfect across them all. So there might be some slight stretching of images depending upon the specific phone's screen size. Also Android devices are typically lower quality in display than the iPhone which might also account for some small bugs.
With the exception of some of the new Flagship Android Devices you may experience some appearance difference.
But one good thing about Android is that their App store has no approval process so we can upload your App to it and be almost instantly approved.
For more information on the fragmentation of the Android Market, see this article!