Indian mustard vs mustard greens

Indian mustard and mustard greens both are nouns.

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

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

Other synonyms of Indian mustard include leaf mustard, mustard.

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