android vs OS

android and OS both are nouns.

Word	Noun	Adjective	Verb	Adverb
android	Yes	No	No	No
OS	Yes	No	No	No

As nouns, OS is a hypernym of android; that is, OS is a word with a broader meaning than android:

android: An operating system from Google for mobile devices
OS: (computer science) software that controls the execution of computer programs and may provide various services

Other hypernyms of android include operating system.

android (noun)	OS (noun)
an automaton that resembles a human being	the left eye
An operating system from Google for mobile devices	(computer science) software that controls the execution of computer programs and may provide various services