juvenile vs puerile

juvenile is a noun but puerile is not a noun.

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

As adjectives, juvenile and puerile are synonyms defined as:

Other synonyms of juvenile include adolescent, jejune.

juvenile (noun)	puerile (noun)
a young person, not fully developed

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