OR vs U.S.

OR and U.S. both are nouns.

Word	Noun	Adjective	Verb	Adverb
OR	Yes	No	No	No
U.S.	Yes	No	No	No

OR (noun)	U.S. (noun)
a room in a hospital equipped for the performance of surgical operations	the executive and legislative and judicial branches of the federal government of the United States
a state in northwestern United States on the Pacific with capital Salem	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