centrist vs middle-of-the-road

centrist is a noun but middle-of-the-road is not a noun.

Word	Noun	Adjective	Verb	Adverb
centrist	Yes	Yes	No	No
middle-of-the-road	No	Yes	No	No

As adjectives, centrist and middle-of-the-road are synonyms defined as:

centrist and middle-of-the-road: supporting or pursuing a course of action that is neither liberal nor conservative

centrist (noun)	middle-of-the-road (noun)
a person who takes a position in the political center

centrist (adjective)	middle-of-the-road (adjective)
supporting or pursuing a course of action that is neither liberal nor conservative	supporting or pursuing a course of action that is neither liberal nor conservative
	not extreme, especially in political views