D.C. vs Washington D.C.

D.C. and Washington D.C. both are nouns.

Word	Noun	Adjective	Verb	Adverb
D.C.	Yes	No	No	No
Washington D.C.	Yes	No	No	No

D.C. (noun)	Washington D.C. (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 capital of the United States in the District of Columbia and a tourist mecca; George Washington commissioned Charles L'Enfant to lay out the city in 1791