American capital vs Capitol Hill

American capital and Capitol Hill both are nouns.

Word	Noun	Adjective	Verb	Adverb
American capital	Yes	No	No	No
Capitol Hill	Yes	No	No	No

American capital (noun)	Capitol Hill (noun)
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	a hill in Washington, D.C., where the Capitol Building sits and Congress meets