Accommodating a kernel by renaming GNU as GNU/Linux was the major-most mistake by free software movement. Android guys refrained from repeating that mistake as they never bothered to name themselves as Android/Linux.
Just because free software people compromised and agreed to recall GNU as GNU/Linux, there occurred all the confusion that Linux is something greater than kernel almost an operating system although it has never been one and later-on development of Android has decisively proved that. The fact has always been limited up to the extent that there are a few operating systems such as GNU and Android which accommodates Linux kernel in their code.
When Richard Stallman was writing a new operating system as free software in 1983, he had to name it distinctively but meaningfully in its historical consequence. So he decided to name that something that is ‘Not Unix’. To do so he tried to find out a word ending with ‘nu’. His search ended up at an animal usually found in sub-Saharan forests of Africa named ‘gnu’. Thus the new operating system was named for ‘GNU is Not UNIX’.
Indeed GNU was not UNIX but it needed a kernel to get completed. That was got written by Linus Torvalds in Helsinki in 1991 so named as ‘Linux’. By 2008 using same Linux kernel another operating system for mobile devices got released that is known as Android. Like nobody bothers to call that Linux, nobody is correct in calling GNU also as Linux. In fact Linux has become a widely used kernel in at-least two major operating systems, which actually are GNU and Android.