showpiece vs piece de resistance

showpiece and piece de resistance both are nouns.

Word	Noun	Adjective	Verb	Adverb
showpiece	Yes	No	No	No
piece de resistance	Yes	No	No	No

As nouns, showpiece and piece de resistance are synonyms defined as:

showpiece and piece de resistance: the outstanding item (the prize piece or main exhibit) in a collection

Other synonyms of showpiece include collector's item.

showpiece (noun)	piece de resistance (noun)
the outstanding item (the prize piece or main exhibit) in a collection	the outstanding item (the prize piece or main exhibit) in a collection
	the most important dish of a meal