United States vs State Department

United States and State Department both are nouns.

Word	Noun	Adjective	Verb	Adverb
United States	Yes	No	No	No
State Department	Yes	No	No	No

United States (noun)	State Department (noun)
the executive and legislative and judicial branches of the federal government of the United States	the federal department in the United States that sets and maintains foreign policies
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 department of government in one of the 50 states