Android tends to use patched kernels, but the diffs are getting smaller (Google made it an explicit goal to bring their fork back to mainline). The bigger issue is the weird userland; a Linux kernel is one thing, but bionic is not a libc meant to run anything but Android, and toybox is no GNU coreutils.

True. I was only referring to Linux itself (i.e., the kernel), because that's what I understood the parent commenter to be referring to.