national capital vs Reykjavik

national capital and Reykjavik both are nouns.

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

national capital (noun)	Reykjavik (noun)
the capital city of a nation	the capital and chief port of Iceland on the southwestern coast of Iceland; buildings are heated by natural hot water