PRC vs mainland China

PRC and mainland China both are nouns.

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

As nouns, PRC and mainland China are synonyms defined as:

PRC and mainland China: a communist nation that covers a vast territory in eastern Asia; the most populous country in the world

Other synonyms of PRC include Cathay, China, Communist China, People's Republic of China, Red China.

PRC (noun)	mainland China (noun)
a communist nation that covers a vast territory in eastern Asia; the most populous country in the world	a communist nation that covers a vast territory in eastern Asia; the most populous country in the world