ONI vs bureau

ONI and bureau both are nouns.

Word	Noun	Adjective	Verb	Adverb
ONI	Yes	No	No	No
bureau	Yes	No	No	No

As nouns, bureau is a hypernym of ONI; that is, bureau is a word with a broader meaning than ONI:

ONI: the military intelligence agency that provides for the intelligence and counterintelligence and investigative and security requirements of the United States Navy
bureau: an administrative unit of government

Other hypernyms of ONI include agency, authority, federal agency, government agency, office.

ONI (noun)	bureau (noun)
the military intelligence agency that provides for the intelligence and counterintelligence and investigative and security requirements of the United States Navy	furniture with drawers for keeping clothes
	an administrative unit of government