work of art vs fine art

work of art and fine art both are nouns.

Word	Noun	Adjective	Verb	Adverb
work of art	Yes	No	No	No
fine art	Yes	No	No	No

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

work of art: art that is a product of one of the fine arts (especially a painting or sculpture of artistic merit)
fine art: the products of human creativity; works of art collectively

Other hypernyms of work of art include art.

work of art (noun)	fine art (noun)
art that is a product of one of the fine arts (especially a painting or sculpture of artistic merit)	the products of human creativity; works of art collectively