Seems I created a little confusion with my post about the Nebulas. Here are the formal definitions, quoted from the Nebula® Rules:
- Short Story: less than 7,500 words.
- Novelette: at least 7,500 words but less than 17,500 words.
- Novella: at least 17,500 words but less than 40,000 words.
- Novel: 40,000 words or more. At the author's request, a novella-length work published individually, rather than as part of a collection or an anthology, shall appear in the novel category.
The Nebula, by the way, is awarded yearly by the Science Fiction and Fantasy Writers of America (SFWA) and is a peer award voted on by the active membership of SFWA, or at least those who have time to read.
The Hugo is awarded yearly by the membership of the annual World Science Fiction Convention (worldcon), and is a fan award. (Some of those fans are also members of SFWA, but most are simply avid readers and, well, fans.)
If you'd like to know more about the Nebula Awards, browse the many entries on SFWA's Nebula Awards page.