whiting vs saltwater fish

whiting and saltwater fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
whiting	Yes	No	No	No
saltwater fish	Yes	No	No	No

As nouns, saltwater fish is a hypernym of whiting; that is, saltwater fish is a word with a broader meaning than whiting:

whiting: flesh of any of a number of slender food fishes especially of Atlantic coasts of North America
saltwater fish: flesh of fish from the sea used as food

As nouns, saltwater fish is a hypernym of whiting; that is, saltwater fish is a word with a broader meaning than whiting:

whiting (noun)	saltwater fish (noun)
a food fish of the Atlantic waters of Europe resembling the cod; sometimes placed in genus Gadus	flesh of fish from the sea used as food
any of several food fishes of North American coastal waters
found off Atlantic coast of North America
a small fish of the genus Sillago; excellent food fish
flesh of any of a number of slender food fishes especially of Atlantic coasts of North America
flesh of a cod-like fish of the Atlantic waters of Europe