antitoxin vs antivenin

antitoxin and antivenin both are nouns.

Word	Noun	Adjective	Verb	Adverb
antitoxin	Yes	No	No	No
antivenin	Yes	No	No	No

As nouns, antivenin is a hyponym of antitoxin; that is, antivenin is a word with a more specific, narrower meaning than antitoxin:

antitoxin: an antibody that can neutralize a specific toxin
antivenin: an antitoxin that counteracts the effects of venom from the bite of a snake or insect or other animal

Other hyponyms of antitoxin include antivenene, tetanus antitoxin.

antitoxin (noun)	antivenin (noun)
an antibody that can neutralize a specific toxin	an antitoxin that counteracts the effects of venom from the bite of a snake or insect or other animal