young woman vs woman

young woman and woman both are nouns.

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

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

Other hypernyms of young woman include adult female.

young woman (noun)	woman (noun)
a young female	women as a class
	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