District of Columbia vs United States

District of Columbia and United States both are nouns.

Word	Noun	Adjective	Verb	Adverb
District of Columbia	Yes	No	No	No
United States	Yes	No	No	No

District of Columbia (noun)	United States (noun)
the district occupied entirely by the city of Washington; chosen by George Washington as the site of the capital of the United States and created out of land ceded by Maryland and Virginia	the executive and legislative and judicial branches of the federal government 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