Oahu vs H.I.

Oahu and H.I. both are nouns.

Word	Noun	Adjective	Verb	Adverb
Oahu	Yes	No	No	No
H.I.	Yes	No	No	No

Oahu (noun)	H.I. (noun)
an island of central Hawaii (between Molokai and Kauai); the chief island of the state	a group of volcanic and coral islands in the central Pacific