arsenous oxide vs trioxide

arsenous oxide and trioxide both are nouns.

Word	Noun	Adjective	Verb	Adverb
arsenous oxide	Yes	No	No	No
trioxide	Yes	No	No	No

As nouns, trioxide is a hypernym of arsenous oxide; that is, trioxide is a word with a broader meaning than arsenous oxide:

arsenous oxide: a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer
trioxide: an oxide containing three atoms of oxygen in the molecule

arsenous oxide (noun)	trioxide (noun)
a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer	an oxide containing three atoms of oxygen in the molecule