puppy vs spring chicken

puppy and spring chicken both are nouns.

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

As nouns, spring chicken is a hypernym of puppy; that is, spring chicken is a word with a broader meaning than puppy:

Other hypernyms of puppy include young person, younker, youth.

puppy (noun)	spring chicken (noun)
a young dog	a young chicken having tender meat
an inexperienced young person	a young person (especially a young man or boy)