Masqat vs national capital

Masqat and national capital both are nouns.

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

Masqat (noun)	national capital (noun)
a port on the Gulf of Oman and capital of the sultanate of Oman	the capital city of a nation