Gallus gallus vs gallina

Gallus gallus and gallina both are nouns.

Word	Noun	Adjective	Verb	Adverb
Gallus gallus	Yes	No	No	No
gallina	Yes	No	No	No

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

Gallus gallus: a jungle fowl of southeastern Asia that is considered ancestral to the domestic fowl
gallina: small Asiatic wild bird; believed to be ancestral to domestic fowl

Other hypernyms of Gallus gallus include jungle fowl.

Gallus gallus (noun)	gallina (noun)
a jungle fowl of southeastern Asia that is considered ancestral to the domestic fowl	small Asiatic wild bird; believed to be ancestral to domestic fowl
a domestic fowl bred for flesh or eggs; believed to have been developed from the red jungle fowl