barium oxide vs barium protoxide

barium oxide and barium protoxide both are nouns.

Word	Noun	Adjective	Verb	Adverb
barium oxide	Yes	No	No	No
barium protoxide	Yes	No	No	No

As nouns, barium oxide and barium protoxide are synonyms defined as:

barium oxide and barium protoxide: an oxide of barium; a whitish toxic powder

Other synonyms of barium oxide include barium monoxide.

barium oxide (noun)	barium protoxide (noun)
an oxide of barium; a whitish toxic powder	an oxide of barium; a whitish toxic powder