chef-d'oeuvre vs masterpiece

chef-d'oeuvre and masterpiece both are nouns.

Word	Noun	Adjective	Verb	Adverb
chef-d'oeuvre	Yes	No	No	No
masterpiece	Yes	No	No	No

As nouns, chef-d'oeuvre and masterpiece are synonyms defined as:

chef-d'oeuvre and masterpiece: the most outstanding work of a creative artist or craftsman

chef-d'oeuvre (noun)	masterpiece (noun)
the most outstanding work of a creative artist or craftsman	an outstanding achievement
	the most outstanding work of a creative artist or craftsman