white tie vs bow-tie

white tie and bow-tie both are nouns.

Word	Noun	Adjective	Verb	Adverb
white tie	Yes	No	No	No
bow-tie	Yes	No	No	No

As nouns, bow-tie is a hypernym of white tie; that is, bow-tie is a word with a broader meaning than white tie:

Other hypernyms of white tie include bow tie, bowtie.

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