objet d'art vs work of art

objet d'art and work of art both are nouns.

Word	Noun	Adjective	Verb	Adverb
objet d'art	Yes	No	No	No
work of art	Yes	No	No	No

As nouns, work of art is a hypernym of objet d'art; that is, work of art is a word with a broader meaning than objet d'art:

objet d'art: a work of art of some artistic value
work of art: art that is a product of one of the fine arts (especially a painting or sculpture of artistic merit)

objet d'art (noun)	work of art (noun)
a work of art of some artistic value	art that is a product of one of the fine arts (especially a painting or sculpture of artistic merit)