national capital vs capital of Azerbaijan

national capital and capital of Azerbaijan both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
capital of Azerbaijan	Yes	No	No	No

national capital (noun)	capital of Azerbaijan (noun)
the capital city of a nation	a port city on the Caspian Sea that is the capital of Azerbaijan and an important center for oil production