juvenile vs younker

juvenile and younker both are nouns.

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

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

juvenile (noun)	younker (noun)
a young person, not fully developed	a young person (especially a young man or boy)

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