greenmarket vs farmer's market

greenmarket and farmer's market both are nouns.

Word	Noun	Adjective	Verb	Adverb
greenmarket	Yes	No	No	No
farmer's market	Yes	No	No	No

As nouns, greenmarket and farmer's market are synonyms defined as:

greenmarket and farmer's market: an open-air marketplace for farm products

Other synonyms of greenmarket include green market.

greenmarket (noun)	farmer's market (noun)
an open-air marketplace for farm products	an open-air marketplace for farm products