luau vs fiesta

luau and fiesta both are nouns.

Word	Noun	Adjective	Verb	Adverb
luau	Yes	No	No	No
fiesta	Yes	No	No	No

As nouns, fiesta is a hypernym of luau; that is, fiesta is a word with a broader meaning than luau:

luau: an elaborate Hawaiian feast or party (especially one accompanied by traditional foods and entertainment)
fiesta: an elaborate party (often outdoors)

Other hypernyms of luau include feast, fete.

luau (noun)	fiesta (noun)
an elaborate Hawaiian feast or party (especially one accompanied by traditional foods and entertainment)	an elaborate party (often outdoors)