national capital vs capital of Bahrain

national capital and capital of Bahrain both are nouns.

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

national capital (noun)	capital of Bahrain (noun)
the capital city of a nation	the capital of Bahrain; located at the northern end of Bahrain Island