There are several hundred different Android smartphones and tablets on the market, and the one thing they have in common (more or less) is the version of the Android operating system they run.
Why More or Less?
Android vendors can add interface elements and applications specific to their brands, which is how they try to distinguish themselves from their competitors. Therefore, although Android devices from two vendors with the same OS version are basically the same, they often have different ways of doing things. For more details, see
Android,
Android versions,
Android fragmentation,
Google Nexus and
Android.