showpiece vs curio

showpiece and curio both are nouns.

Word	Noun	Adjective	Verb	Adverb
showpiece	Yes	No	No	No
curio	Yes	No	No	No

As nouns, curio is a hypernym of showpiece; that is, curio is a word with a broader meaning than showpiece:

showpiece: the outstanding item (the prize piece or main exhibit) in a collection
curio: something unusual -- perhaps worthy of collecting

Other hypernyms of showpiece include curiosity, oddity, oddment, peculiarity, rarity.

showpiece (noun)	curio (noun)
the outstanding item (the prize piece or main exhibit) in a collection	something unusual -- perhaps worthy of collecting