Potomac River vs Old Dominion State

Potomac River and Old Dominion State both are nouns.

Word	Noun	Adjective	Verb	Adverb
Potomac River	Yes	No	No	No
Old Dominion State	Yes	No	No	No

Potomac River (noun)	Old Dominion State (noun)
a river in the east central United States; rises in West Virginia in the Appalachian Mountains and flows eastward, forming the boundary between Maryland and Virginia, to the Chesapeake Bay	a state in the eastern United States; one of the original 13 colonies; one of the Confederate States in the American Civil War