national capital vs Kingston

national capital and Kingston both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
Kingston	Yes	No	No	No

national capital (noun)	Kingston (noun)
the capital city of a nation	capital and largest city of Jamaica
	a town on the Hudson River in New York
	a town in southeast Ontario on Lake Ontario near the head of the Saint Lawrence River