Pearl River vs mainland China

Pearl River and mainland China both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pearl River	Yes	No	No	No
mainland China	Yes	No	No	No

Pearl River (noun)	mainland China (noun)
a river in Mississippi that flows southward to the Gulf of Mexico	a communist nation that covers a vast territory in eastern Asia; the most populous country in the world
a river in southeast China that flows into the South China Sea