fancy dress vs masquerade

fancy dress and masquerade both are nouns.

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

As nouns, fancy dress and masquerade are synonyms defined as:

fancy dress and masquerade: a costume worn as a disguise at a masquerade party

Other synonyms of fancy dress include masquerade costume.

fancy dress (noun)	masquerade (noun)
a costume worn as a disguise at a masquerade party	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 (verb)	masquerade (verb)
	pretend to be someone or something that you are not
	take part in a masquerade