swallowtail vs swallow-tailed coat

swallowtail and swallow-tailed coat both are nouns.

Word	Noun	Adjective	Verb	Adverb
swallowtail	Yes	No	No	No
swallow-tailed coat	Yes	No	No	No

As nouns, swallowtail and swallow-tailed coat are synonyms defined as:

swallowtail and swallow-tailed coat: a man's full-dress jacket with two long tapering tails at the back

Other synonyms of swallowtail include morning coat.

swallowtail (noun)	swallow-tailed coat (noun)
a man's full-dress jacket with two long tapering tails at the back	a man's full-dress jacket with two long tapering tails at the back