spring chicken vs youth

spring chicken and youth both are nouns.

Word	Noun	Adjective	Verb	Adverb
spring chicken	Yes	No	No	No
youth	Yes	No	No	No

As nouns, spring chicken and youth are synonyms defined as:

spring chicken and youth: a young person (especially a young man or boy)

Other synonyms of spring chicken include young person, younker.

spring chicken (noun)	youth (noun)
a young chicken having tender meat	the freshness and vitality characteristic of a young person
a young person (especially a young man or boy)	young people collectively
	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