national capital vs Astana

national capital and Astana both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
Astana	Yes	No	No	No

national capital (noun)	Astana (noun)
the capital city of a nation	remote city of Kazakhstan that (ostensibly for security reasons) was made the capital in 1998