white arsenic vs arsenous oxide

white arsenic and arsenous oxide both are nouns.

Word	Noun	Adjective	Verb	Adverb
white arsenic	Yes	No	No	No
arsenous oxide	Yes	No	No	No

As nouns, white arsenic and arsenous oxide are synonyms defined as:

white arsenic and arsenous oxide: a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer

Other synonyms of white arsenic include arsenic, arsenic trioxide, arsenous anhydride, ratsbane.

white arsenic (noun)	arsenous oxide (noun)
a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer	a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer