leaf mustard vs Brassica juncea

leaf mustard and Brassica juncea both are nouns.

Word	Noun	Adjective	Verb	Adverb
leaf mustard	Yes	No	No	No
Brassica juncea	Yes	No	No	No

As nouns, leaf mustard and Brassica juncea are synonyms defined as:

Other synonyms of leaf mustard include chinese mustard, gai choi, indian mustard.

leaf mustard (noun)	Brassica juncea (noun)
leaves eaten as cooked greens	Asiatic mustard used as a potherb
Asiatic mustard used as a potherb