neurotoxin vs saxitoxin

neurotoxin and saxitoxin both are nouns.

Word	Noun	Adjective	Verb	Adverb
neurotoxin	Yes	No	No	No
saxitoxin	Yes	No	No	No

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

neurotoxin: any toxin that affects neural tissues
saxitoxin: a powerful neurotoxin produced by certain dinoflagellates found in red tides; it can accumulate in mollusks that feed on the dinoflagellates and cause food poisoning to humans

Other hyponyms of neurotoxin include botulinum toxin, domoic acid, kokoi venom, tetrodotoxin.

neurotoxin (noun)	saxitoxin (noun)
any toxin that affects neural tissues	a powerful neurotoxin produced by certain dinoflagellates found in red tides; it can accumulate in mollusks that feed on the dinoflagellates and cause food poisoning to humans