fiction vs literary work

fiction and literary work both are nouns.

Word	Noun	Adjective	Verb	Adverb
fiction	Yes	No	No	No
literary work	Yes	No	No	No

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

fiction: a literary work based on the imagination and not necessarily on fact
literary work: imaginative or creative writing

Other hypernyms of fiction include literary composition.

fiction (noun)	literary work (noun)
a literary work based on the imagination and not necessarily on fact	imaginative or creative writing
a deliberately false or improbable account