Linux is the kernel, not the userland. So for "most"
intents, yes,
Android is linux.
There are some measurable differences, there is an ongoing attempt to
re-unify them.
Additionally, ZDNET is the "fawks news" of the internet.
Try to take
anything they post with a few kilos of salt.
There are several studies all of which suggest the Android user base will
exceed Windows next year, and some good evidence that overall Linux
passed Windows a while back when you count all the DVRs, TV sets, etc
with it in.
The Android one however is much more significant because its a product
buying/downloading user base.
Alan