Communist China vs Cathay

Communist China and Cathay both are nouns.

Word	Noun	Adjective	Verb	Adverb
Communist China	Yes	No	No	No
Cathay	Yes	No	No	No

As nouns, Communist China and Cathay are synonyms defined as:

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

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

Communist China (noun)	Cathay (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