sulfamethazine vs sulfa drug

sulfamethazine and sulfa drug both are nouns.

Word	Noun	Adjective	Verb	Adverb
sulfamethazine	Yes	No	No	No
sulfa drug	Yes	No	No	No

As nouns, sulfa drug is a hypernym of sulfamethazine; that is, sulfa drug is a word with a broader meaning than sulfamethazine:

sulfamethazine: a sulfa drug used like sulfadiazine and also in veterinary medicine
sulfa drug: antibacterial consisting of any of several synthetic organic compounds capable of inhibiting the growth of bacteria that require PABA

Other hypernyms of sulfamethazine include sulfa, sulfonamide, sulpha.

sulfamethazine (noun)	sulfa drug (noun)
a sulfa drug used like sulfadiazine and also in veterinary medicine	antibacterial consisting of any of several synthetic organic compounds capable of inhibiting the growth of bacteria that require PABA