Android is *NOT* Linux based, it is merely Linux hosted. Android is its own OS, its own environment.
And now you know why Richard Stallman was right about calling the familiar desktop and server operating system "GNU/Linux". Android has a completely different userland on top of the same Linux kernel that underlies GNU/Linux.
No. Android is not some sort of userland, not some sort of GUI layer. It is its own thing. Android is a basically a Java based OS where the hardware and the host operating system are both abstracted away.