Asia vs mainland China

Asia and mainland China both are nouns.

Word	Noun	Adjective	Verb	Adverb
Asia	Yes	No	No	No
mainland China	Yes	No	No	No

Asia (noun)	mainland China (noun)
the nations of the Asian continent collectively	a communist nation that covers a vast territory in eastern Asia; the most populous country in the world
the largest continent with 60% of the earth's population; it is joined to Europe on the west to form Eurasia; it is the site of some of the world's earliest civilizations