Android apps are generally written in Java using the Android SDK. The main task with Android apps is to enable testing on the multitude of different hand sets.
We tend to use third parties to perform these tests. The process is more involved than with iOS because handsets interpret the Android APIs in more varied ways, so exhibit more varied functionality. Plus while iOS users upgrade their device OS to the latest version pretty regularly, Android phones are rarely updated (generally because the manufacturers don’t provide the updates).
This results in a wide variety of hardware and software versions all trying to use your app. Hence in general preparing and Android app is more expensive and time consuming than for iOS.
Android apps are hosted on a Google Play account. Android apps are not curated, so do not have to undergo a five day wait before publishing. Hence updates and initial upload can take less than two hours to become live in the Google Play store.
The flip side is that Google generally runs automated scans on the apps, and if they do find any issues (such as copyright infringement) they are quick to de-list the app automatically. They also run a much smaller cohort of support staff than Apple, so it can be extremely difficult to turn around any adverse decisions.