USA vs OR

USA and OR both are nouns.

Word	Noun	Adjective	Verb	Adverb
USA	Yes	No	No	No
OR	Yes	No	No	No

USA (noun)	OR (noun)
the army of the United States of America; the agency that organizes and trains soldiers for land warfare	a room in a hospital equipped for the performance of surgical operations
North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776	a state in northwestern United States on the Pacific with capital Salem