teenager vs juvenile

teenager and juvenile both are nouns.

Word	Noun	Adjective	Verb	Adverb
teenager	Yes	No	No	No
juvenile	Yes	Yes	No	No

As nouns, juvenile is a hypernym of teenager; that is, juvenile is a word with a broader meaning than teenager:

Other hypernyms of teenager include juvenile person.

teenager (noun)	juvenile (noun)
a juvenile between the onset of puberty and maturity	a young person, not fully developed

teenager (adjective)	juvenile (adjective)
	of or relating to or characteristic of or appropriate for children or young people
	displaying or suggesting a lack of maturity