tailcoat vs white tie

tailcoat and white tie both are nouns.

Word	Noun	Adjective	Verb	Adverb
tailcoat	Yes	No	No	No
white tie	Yes	No	No	No

As nouns, tailcoat and white tie are synonyms defined as:

tailcoat and white tie: formalwear consisting of full evening dress for men

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

tailcoat (noun)	white tie (noun)
formalwear consisting of full evening dress for men	bow tie worn as part of a man's formal evening dress
	formalwear consisting of full evening dress for men