iTunes and Google Play Comparison
Areas of Foucus Within the Store
Layout On Mobile Store
Quality of Both
Apple has a more streamlined process than Google does. Once you pay a one-time fee for a developers license with Apple, you can submit any apps with the help of an SDK. When the app store was first created, it took around two weeks to wait for approval of an app. now it only takes a few days. And Apple has introduced improved feedback. They've also tried to make sure that apps have an actual purpose, and aren't just around to be a domain for advertising.
With the Android/Google market you need to register as a developer also. The fee is priced at 25 dollars for a developers license. But to pay you need to have a Google checkout account. Then you submit the application package, along with at least two screen shots and a high res. icon for the app. Google is more likely to have buggy apps because the submission process is easier to complete and just about anyone can do it.