Gadus merlangus vs gadoid

Gadus merlangus and gadoid both are nouns.

Word	Noun	Adjective	Verb	Adverb
Gadus merlangus	Yes	No	No	No
gadoid	Yes	No	No	No

As nouns, gadoid is a hypernym of Gadus merlangus; that is, gadoid is a word with a broader meaning than Gadus merlangus:

Gadus merlangus: a food fish of the Atlantic waters of Europe resembling the cod; sometimes placed in genus Gadus
gadoid: a soft-finned fish of the family Gadidae

Other hypernyms of Gadus merlangus include gadoid fish.

Gadus merlangus (noun)	gadoid (noun)
a food fish of the Atlantic waters of Europe resembling the cod; sometimes placed in genus Gadus	a soft-finned fish of the family Gadidae