woman vs grownup

woman and grownup both are nouns.

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

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

Other hypernyms of woman include adult, female, female person.

woman (noun)	grownup (noun)
women as a class	a fully developed person from maturity onward
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

woman (adjective)	grownup (adjective)
	(of animals) fully developed