grocery vs grocery store

grocery and grocery store both are nouns.

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

As nouns, grocery and grocery store are synonyms defined as:

Other synonyms of grocery include food market, market.

grocery (noun)	grocery store (noun)
a marketplace where groceries are sold	a marketplace where groceries are sold
(usually plural) consumer goods sold by a grocer