Sino-Tibetan vs mainland China

Sino-Tibetan and mainland China both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sino-Tibetan	Yes	No	No	No
mainland China	Yes	No	No	No

Sino-Tibetan (noun)	mainland China (noun)
the family of tonal languages spoken in eastern Asia	a communist nation that covers a vast territory in eastern Asia; the most populous country in the world