different between tailcoat vs swallowtail

English

tail +? coat

tailcoat (plural tailcoats)

swallow +? tail

swallowtail (plural swallowtails)

The forked tail of a swallow.
Anything, such as a burgee, of a similar forked shape.
A type of tailcoat with two long tapering tails.^Wp
- It was April 22, 1831, and a young man was walking down Whitehall in the direction of Parliament Street. He wore shepherd's plaid trousers and the swallow-tail coat of the day, with a figured muslin cravat wound about his wide-spread collar.
Any of various butterflies of the family Papilionidae, many of which have a long extension to each hindwing.

Send