spring chicken vs young person

spring chicken and young person both are nouns.

Word	Noun	Adjective	Verb	Adverb
spring chicken	Yes	No	No	No
young person	Yes	No	No	No

As nouns, spring chicken and young person are synonyms defined as:

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

Other synonyms of spring chicken include younker, youth.

spring chicken (noun)	young person (noun)
a young chicken having tender meat	a young person (especially a young man or boy)
a young person (especially a young man or boy)