juvenile vs teenager

juvenile and teenager both are nouns.

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

As nouns, teenager is a hyponym of juvenile; that is, teenager is a word with a more specific, narrower meaning than juvenile:

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

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