State Department vs USA

State Department and USA both are nouns.

Word	Noun	Adjective	Verb	Adverb
State Department	Yes	No	No	No
USA	Yes	No	No	No

State Department (noun)	USA (noun)
the federal department in the United States that sets and maintains foreign policies	the army of the United States of America; the agency that organizes and trains soldiers for land warfare
a department of government in one of the 50 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