clerical collar vs Roman collar

clerical collar and Roman collar both are nouns.

Word	Noun	Adjective	Verb	Adverb
clerical collar	Yes	No	No	No
Roman collar	Yes	No	No	No

As nouns, clerical collar and Roman collar are synonyms defined as:

clerical collar and Roman collar: a stiff white collar with no opening in the front; a distinctive symbol of the clergy

Other synonyms of clerical collar include dog collar.

clerical collar (noun)	Roman collar (noun)
a stiff white collar with no opening in the front; a distinctive symbol of the clergy	a stiff white collar with no opening in the front; a distinctive symbol of the clergy