sulfur mustard vs mustard agent

sulfur mustard and mustard agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
sulfur mustard	Yes	No	No	No
mustard agent	Yes	No	No	No

As nouns, sulfur mustard and mustard agent are synonyms defined as:

sulfur mustard and mustard agent: a toxic war gas with sulfide based compounds that raises blisters and attacks the eyes and lungs; there is no known antidote

Other synonyms of sulfur mustard include blistering agent, dichloroethyl sulfide, mustard gas.

sulfur mustard (noun)	mustard agent (noun)
a toxic war gas with sulfide based compounds that raises blisters and attacks the eyes and lungs; there is no known antidote	a toxic war gas with sulfide based compounds that raises blisters and attacks the eyes and lungs; there is no known antidote