national capital vs capital of Serbia and Montenegro

national capital and capital of Serbia and Montenegro both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
capital of Serbia and Montenegro	Yes	No	No	No

national capital (noun)	capital of Serbia and Montenegro (noun)
the capital city of a nation	capital and largest city of Serbia and Montenegro; situated on the Danube