food market vs marketplace

food market and marketplace both are nouns.

Word	Noun	Adjective	Verb	Adverb
food market	Yes	No	No	No
marketplace	Yes	No	No	No

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

food market: a marketplace where groceries are sold
marketplace: an area in a town where a public mercantile establishment is set up

Other hypernyms of food market include market, market place, mart.

food market (noun)	marketplace (noun)
a marketplace where groceries are sold	the world of commercial activity where goods and services are bought and sold
	an area in a town where a public mercantile establishment is set up