youth vs juvenility

youth and juvenility both are nouns.

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

As nouns, youth and juvenility are synonyms defined as:

youth and juvenility: the freshness and vitality characteristic of a young person

Other synonyms of youth include youthfulness.

youth (noun)	juvenility (noun)
the freshness and vitality characteristic of a young person	the freshness and vitality characteristic of a young person
young people collectively	lacking and evidencing lack of experience of life
a young person (especially a young man or boy)
early maturity; the state of being young or immature or inexperienced
the time of life between childhood and maturity
an early period of development