USA vs staff member

USA and staff member both are nouns.

Word	Noun	Adjective	Verb	Adverb
USA	Yes	No	No	No
staff member	Yes	No	No	No

USA (noun)	staff member (noun)
the army of the United States of America; the agency that organizes and trains soldiers for land warfare	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