greenmarket vs green market

greenmarket and green market both are nouns.

Word	Noun	Adjective	Verb	Adverb
greenmarket	Yes	No	No	No
green market	Yes	No	No	No

As nouns, greenmarket and green market are synonyms defined as:

Other synonyms of greenmarket include farmer's market.

greenmarket (noun)	green market (noun)
an open-air marketplace for farm products	an open-air marketplace for farm products