whitefish vs food fish

whitefish and food fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
whitefish	Yes	No	No	No
food fish	Yes	No	No	No

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

whitefish: silvery herring-like freshwater food fish of cold lakes of the Northern Hemisphere
food fish: any fish used for food by human beings

Other hypernyms of whitefish include malacopterygian, soft-finned fish.

whitefish (noun)	food fish (noun)
silvery herring-like freshwater food fish of cold lakes of the Northern Hemisphere	any fish used for food by human beings
flesh of salmon-like or trout-like cold-water fish of cold lakes of the Northern Hemisphere
any market fish--edible saltwater fish or shellfish--except herring