mustard greens vs Indian mustard

mustard greens and Indian mustard both are nouns.

Word	Noun	Adjective	Verb	Adverb
mustard greens	Yes	No	No	No
Indian mustard	Yes	No	No	No

As nouns, mustard greens and Indian mustard are synonyms defined as:

Other synonyms of mustard greens include leaf mustard, mustard.

mustard greens (noun)	Indian mustard (noun)
leaves eaten as cooked greens	leaves eaten as cooked greens