national capital vs capital of Thailand

national capital and capital of Thailand both are nouns.

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

national capital (noun)	capital of Thailand (noun)
the capital city of a nation	the capital and largest city and chief port of Thailand; a leading city in southeastern Asia; noted for Buddhist architecture