spring chicken vs Gallus gallus

spring chicken and Gallus gallus both are nouns.

Word	Noun	Adjective	Verb	Adverb
spring chicken	Yes	No	No	No
Gallus gallus	Yes	No	No	No

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

spring chicken: a young chicken having tender meat
Gallus gallus: a domestic fowl bred for flesh or eggs; believed to have been developed from the red jungle fowl

Other hypernyms of spring chicken include chicken.

spring chicken (noun)	Gallus gallus (noun)
a young chicken having tender meat	a jungle fowl of southeastern Asia that is considered ancestral to the domestic fowl
a young person (especially a young man or boy)	a domestic fowl bred for flesh or eggs; believed to have been developed from the red jungle fowl