Once upon a time maybe, nowadays you have to represent yourself, your close community and no one else. STAY IN YOUR LANE WHITE WRITER. All fiction must be autobiographical and not really fiction at all. These are the new rules, you can disagree with them but you can't change them.I think the main difference between the 2 is that fictional writing is generally an attempt to represent someone else's viewpoint whereas songwriting is generally seen as a direct representation of the artists viewpoint.