fancy-dress ball vs masquerade

fancy-dress ball and masquerade both are nouns.

Word	Noun	Adjective	Verb	Adverb
fancy-dress ball	Yes	No	No	No
masquerade	Yes	No	Yes	No

As nouns, masquerade is a hypernym of fancy-dress ball; that is, masquerade is a word with a broader meaning than fancy-dress ball:

Other hypernyms of fancy-dress ball include ball, formal, mask, masque, masquerade party.

fancy-dress ball (noun)	masquerade (noun)
a ball at which guests wear costumes and masks	making a false outward show
	a costume worn as a disguise at a masquerade party
	a party of guests wearing costumes and masks

fancy-dress ball (verb)	masquerade (verb)
	pretend to be someone or something that you are not
	take part in a masquerade