coach dog vs carriage dog

coach dog and carriage dog both are nouns.

Word	Noun	Adjective	Verb	Adverb
coach dog	Yes	No	No	No
carriage dog	Yes	No	No	No

As nouns, coach dog and carriage dog are synonyms defined as:

coach dog and carriage dog: a large breed having a smooth white coat with black or brown spots; originated in Dalmatia

Other synonyms of coach dog include dalmatian.

coach dog (noun)	carriage dog (noun)
a large breed having a smooth white coat with black or brown spots; originated in Dalmatia	a large breed having a smooth white coat with black or brown spots; originated in Dalmatia