allegory vs fable

allegory and fable both are nouns.

Word	Noun	Adjective	Verb	Adverb
allegory	Yes	No	No	No
fable	Yes	No	No	No

As nouns, allegory and fable are synonyms defined as:

Other synonyms of allegory include apologue, parable.

allegory (noun)	fable (noun)
a short moral story (often with animal characters)	a short moral story (often with animal characters)
an expressive style that uses fictional characters and events to describe some subject by suggestive resemblances; an extended metaphor	a story about mythical or supernatural beings or events
a visible symbol representing an abstract idea	a deliberately false or improbable account