preteenager vs juvenile

preteenager and juvenile both are nouns.

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

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

preteenager: a preadolescent boy or girl (usually between 9 and 12 years of age)
juvenile: a young person, not fully developed

Other hypernyms of preteenager include juvenile person.

preteenager (noun)	juvenile (noun)
a preadolescent boy or girl (usually between 9 and 12 years of age)	a young person, not fully developed

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