state capital vs Columbia

state capital and Columbia both are nouns.

Word	Noun	Adjective	Verb	Adverb
state capital	Yes	No	No	No
Columbia	Yes	No	No	No

state capital (noun)	Columbia (noun)
the capital city of a political subdivision of a country	a university in New York City
	capital and largest city in South Carolina; located in central South Carolina
	a university town in central Missouri
	a town in west central Tennessee
	a North American river; rises in southwestern Canada and flows southward across Washington to form the border between Washington and Oregon before emptying into the Pacific; known for its salmon runs in the spring