staff member vs U.S.A.

staff member and U.S.A. both are nouns.

Word	Noun	Adjective	Verb	Adverb
staff member	Yes	No	No	No
U.S.A.	Yes	No	No	No

staff member (noun)	U.S.A. (noun)
an employee who is a member of a staff of workers (especially a member of the staff that works for the President of the United States)	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