youngness vs juvenility

youngness and juvenility both are nouns.

Word	Noun	Adjective	Verb	Adverb
youngness	Yes	No	No	No
juvenility	Yes	No	No	No

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

Other hyponyms of youngness include youth, youthfulness, childishness, puerility.

youngness (noun)	juvenility (noun)
the opposite of oldness	the freshness and vitality characteristic of a young person
	lacking and evidencing lack of experience of life