national capital vs capital of Turkmenistan

national capital and capital of Turkmenistan both are nouns.

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

national capital (noun)	capital of Turkmenistan (noun)
the capital city of a nation	the capital and largest city of Turkmenistan