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The American Traditional Dictionary explains personification as follows: attribute human motivation, representation or behavior to animated objects, animals or natural phenomenology.

Personification: To endow inanimate objects, animals or natural phenomena with human motives, characteristics or behaviors.

Personification is a rhetorical device that ends with human qualities in vivid objects or abstract objects, or is represented as posing as a human figure.

Sorry, I don't know the difference in usage either.

The American Traditional Dictionary defines fable as a short narrative of American nature, which is enlightening or dictionary-oriented, and often uses animals who speak and act like human beings as characters. Fable: a short story usually used to express an enlightening or cautious point of view, usually using animals that talk or act like characters.

The interpretation of fable is: a written, dramatic or painting means, in which characters and events represent abstract thoughts, principles or forces, so the literal meaning has or implies a parallel and deeper symbolic meaning. Fable: an artistic technique in literature, drama or painting, in which characters and events represent abstract ideas, principles or dominance, so that the superficial meaning contains or expresses an equivalent but deeper symbolic meaning.

Fable is a literary genre, and fable is a rhetorical device.