girlfriend vs woman

girlfriend and woman both are nouns.

Word	Noun	Adjective	Verb	Adverb
girlfriend	Yes	No	No	No
woman	Yes	No	No	No

As nouns, woman is a hypernym of girlfriend; that is, woman is a word with a broader meaning than girlfriend:

Other hypernyms of girlfriend include lover, adult female.

As nouns, woman is a hypernym of girlfriend; that is, woman is a word with a broader meaning than girlfriend:

Other hypernyms of girlfriend include friend, adult female.

girlfriend (noun)	woman (noun)
a girl or young woman with whom a man is romantically involved	women as a class
any female friend	an adult female person (as opposed to a man)
	a female person who plays a significant role (wife or mistress or girlfriend) in the life of a particular man