Congregational vs Congregationalist

Congregational is not a noun while Congregationalist is a noun.

Word	Noun	Adjective	Verb	Adverb
Congregational	No	Yes	No	No
Congregationalist	Yes	Yes	No	No

As adjectives, Congregational and Congregationalist are synonyms defined as:

Congregational and Congregationalist: of or pertaining to or characteristic of a Congregational church

Congregational (noun)	Congregationalist (noun)
	a member of the Congregational Church

Congregational (adjective)	Congregationalist (adjective)
of or pertaining to or characteristic of a Congregational church	of or pertaining to or characteristic of a Congregational church