tails vs tail coat

tails and tail coat both are nouns.

Word	Noun	Adjective	Verb	Adverb
tails	Yes	No	No	No
tail coat	Yes	No	No	No

As nouns, tails and tail coat are synonyms defined as:

tails and tail coat: formalwear consisting of full evening dress for men

Other synonyms of tails include dress suit, full dress, tailcoat, white tie, white tie and tails.

tails (noun)	tail coat (noun)
formalwear consisting of full evening dress for men	formalwear consisting of full evening dress for men