No, Android is based on Linux, but it is not a Linux distribution*. Android has :
- Linux kernel;
- Bionic replaces glibc (so all the Android drivers aren't compatible with Mobile Linux, thanks Google... and a lot of Linux projects can't be ported to Android or are hard to port);
- SurfaceFlinger instead of X11, explaining why there is no "ssh -X", Linux chroot needs VNC, etc;
- different memory task management (which kills running softwares without user acknowledgement), so not full multi-tasking;
- no package dependencies (so it is normal to have .apk's with 10 MB where 9.5 MB are repeated libraries).
(*) : I see more differences than similarities between Android with desktop Linux distributions. While Maemo 5 has Linux kernel, glibc, X11, package dependencies, full multitasking, etc. But the definition of Linux distribution is not so rigid. So some people call Android a mobile Linux distribution. More opinions :
http://www.gnu.org/gnu/gnu-linux-faq...xsyswithoutgnu
https://www.gnu.org/philosophy/andro...s-freedom.html
"Android is very different from the GNU/Linux operating system because it contains very little of GNU. Indeed, just about the only component in common between Android and GNU/Linux is Linux, the kernel. People who erroneously think “Linux” refers to the entire GNU/Linux combination get tied in knots by these facts, and make paradoxical statements such as “Android contains Linux, but it isn't Linux.” If we avoid starting from the confusion, the situation is simple: Android contains Linux, but not GNU; thus, Android and GNU/Linux are mostly different."
http://arstechnica.com/gadgets/2009/...or-developers/
"In fact, during a presentation at the Google IO conference, Google engineer Patrick Brady stated unambiguously that Android is not Linux"


iOS also has many parts from MacOS, but iOS <> MacOS.

Windows Phone 8 has many parts of Windows 8 : kernel (Windows NT one), NTFS, Direct X 11, .Net engine, etc. But Windows Phone 8 <> Windows 8.