greengrocery vs food market

greengrocery and food market both are nouns.

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

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

Other hypernyms of greengrocery include grocery, grocery store, market.

greengrocery (noun)	food market (noun)
a greengrocer's grocery store	a marketplace where groceries are sold
groceries sold by a greengrocer