Roman collar vs dog collar

Roman collar and dog collar both are nouns.

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

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

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

Other synonyms of Roman collar include clerical collar.

Roman collar (noun)	dog collar (noun)
a stiff white collar with no opening in the front; a distinctive symbol of the clergy	a collar for a dog
	a stiff white collar with no opening in the front; a distinctive symbol of the clergy
	necklace that fits tightly around a woman's neck