capital of Azerbaijan vs national capital

capital of Azerbaijan and national capital both are nouns.

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

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