supermarket vs grocery

supermarket and grocery both are nouns.

Word	Noun	Adjective	Verb	Adverb
supermarket	Yes	No	No	No
grocery	Yes	No	No	No

As nouns, grocery is a hypernym of supermarket; that is, grocery is a word with a broader meaning than supermarket:

supermarket: a large self-service grocery store selling groceries and dairy products and household goods
grocery: a marketplace where groceries are sold

Other hypernyms of supermarket include food market, grocery store, market.

supermarket (noun)	grocery (noun)
a large self-service grocery store selling groceries and dairy products and household goods	a marketplace where groceries are sold
	(usually plural) consumer goods sold by a grocer