Hollywood was so complicated! Back in the day, it took three categories to honor the writers: Screenplay, which seemed to primarily honor adaptations; Story and Screenplay, which is the equivalent to Original Screenplay; and Story, which we don't have anymore, and which, for some reason was separate from the other category? As best as I can tell, it was used when the Story and the Screenplay were written by different people, so at least it was an attempt to distinguish between the creative individuals who contribute to a film.
Still, there is some understandable confusion, especially when some are credited with "From a story by", which sounds like an adaptation, but often isn't. Like, OK -- it's weird that the original
Roman Holiday is nominated here and in Screenplay, but not in Story
and Screenplay; the confusion also led to a nomination for Louis L'Amour for
Hondo, even though he only wrote the original short story and had no hand in the adaptation. With such problems, it's no wonder the category was discontinued in 1957.
But that's in another four years. 'Til then, here's who benefited...