white tie and tails vs dress suit

white tie and tails and dress suit both are nouns.

Word	Noun	Adjective	Verb	Adverb
white tie and tails	Yes	No	No	No
dress suit	Yes	No	No	No

As nouns, white tie and tails and dress suit are synonyms defined as:

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

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

white tie and tails (noun)	dress suit (noun)
formalwear consisting of full evening dress for men	formalwear consisting of full evening dress for men