will-o'-the-wisp vs fancy

will-o'-the-wisp and fancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
will-o'-the-wisp	Yes	No	No	No
fancy	Yes	Yes	Yes	No

As nouns, fancy is a hypernym of will-o'-the-wisp; that is, fancy is a word with a broader meaning than will-o'-the-wisp:

Other hypernyms of will-o'-the-wisp include fantasy, illusion, phantasy.

will-o'-the-wisp (noun)	fancy (noun)
an illusion that misleads	imagination or fantasy; held by Coleridge to be more casual and superficial than true imagination
a pale light sometimes seen at night over marshy ground	something many people believe that is false
	a predisposition to like something

will-o'-the-wisp (adjective)	fancy (adjective)
	not plain; decorative or ornamented

will-o'-the-wisp (verb)	fancy (verb)
	imagine; conceive of; see in one's mind
	have a fancy or particular liking or desire for