Let me amend the above without editing it to death. See, what's happening here is that a lot of people use strict interpretations of the genres. So, let's look at those strict guidelines. I wrote these up on a lecture about the sub-genre of romance, but it's equally instructive as to the main categories.
Paranormal - Ah, paranormal. The darling of the current market. No other category is so confusingly grouped into one lump. There are any number of sub-subgenres of paranormal, so take a deep breath and let’s go through them:
Futuristic: A futuristic novel is one that is from 2006-infinity, but is EARTH-BASED! This means that you are using humans as they exist on Earth that may or may not interact with other species that have yet to be discovered, or dealing with a world very different than what we know know (whether from natural catastrophe, alien invasion, world politics, etc., etc.) The future world must have rationale that is understandable. For example, humans don't have green blood. They will probably NEVER have green blood, so don't try it. But Vulcans (Star Trek) DO have green blood, so that's okay. Star Trek is a tricky one, because it IS science-fiction, and it IS futuristic, and big chunks of it ARE fantasy. It's generally considered science-fiction, for the record.
Fantasy: The biggest issue with the fantasy sub-genre is the concept of "world-building." Fantasy novels come in two breeds: One is a different world, with creatures that don't exist on earth, that may or may not talk, etc. The other fantasy is "alternate reality." An alternate reality is one which follows Earth history except for one or two things. The Laurell K. Hamilton, Anita Blake world, for example is a good example. Vampires have always existed. But they were hunted like rats -- UNTIL the United States Supreme Court declared them "not dead". Suddenly, vampires could own property, adopt children (since they couldn't bear them on their own), marry, divorce, etc. Probates for "dead" relatives were unwound and life generally was upended. The key to a fantasy romance is making the fantastical elements an equal partner to the regular ones. So the guy is a vampire -- some are jerks and some are sweeties. It's an ELEMENT of the personality, but they don't have to fall into "set" requirements, because it's NOT REAL, so it doesn't have to adhere to known legends.
Science Fiction: This is often confused with futuristic, but the goal of science fiction is the USE OF science in the story. Whether the story is set in 2005 or 3035, hard science that is well thought out is key. The Time Machine or 20,000 Leagues Under the Sea, would be science fiction, but not necessarily futuristic.
Time Travel: Also a close contender for futuristic. After a long and... ahem, spirited discussion among the authors in the FF&P chapter, we determined that the difference between futuristic and time travel is one key element. Susan Grant's The Scarlet Empress was the issue at hand -- should it be entered in the RITA under time travel or under futuristic. The joint decision was made that it was futuristic, because THE HEROINE COULD NOT RETURN HOME. Susan's heroine was cryogenitically frozen and awoken in 2076 to save the world from a "new world order". It was science fiction, and futuristic and was a woman from the past thrown into the future. But we finally all agreed that for time travel to be a key element in the novel, the hero or heroine must have the ABILITY to return to their time, whether or not they choose to do so. Otherwise, it's in a different category.
Paranormal: The key element of a paranormal is LEGEND. Werewolves are legend, and so are vampires, pixies, fairies, doxies, living mummies, etc. A paranormal is PARA or "resembling or imitating" NORMAL "real life". Most vampire romances fit this category. There is a handed down legend or fable or "this really happened!" account of something outside the ordinary that we don't generally believe but aren't complete convinced COULDN'T happen. While it can be set in the future, the past or the present, the key is that everything ELSE is normal, except for the addition of this one element. Now, WITHIN paranormal, there are two additional categories (so
Light Paranormal - Light paranormal deals with creatures that are magical, and that have as their "legend" that they benefit mankind generally. Angels, fairies, Gods/Goddesses, spirits/ghosts, and the like. The storylines are generally that a superior being falls in love with a human or with each other and nobody gets hurt. Think of the movie "Ghost". That's a light paranormal.
Dark Paranormal - These are the creatures of legend that subsist on blood or flesh of humans or other creatures. Vampires, werewolves, doxies, unseelie fey (darker cousins of the fairies), leprechauns, etc. As their legends, they harm people to their own benefit. These storylines deal with the dark creature overcoming their dark nature to fall in love with a human or with each other. Think of the movie "Van Helsing". That's a dark paranormal.
Now, these definitions have NOTHING to do with where the book is shelved. There are only so many places to stock the book, and the editors know this. The lines they buy for are very specific, and yet very broad. If they're buying dark fantasy books, they DON'T want science fiction. They don't want specifically horror plots (where the good guy dies/loses). But that's about it. Most everything else is lumped under a single umbrella. Now, what you want to CALL your book is up to you. You can argue definitions until the cows come home. After your book is published, you can continue to argue that it's not horror even though that's where it's shelved. You can argue it's not science fiction, even though it's right next to an Asimov title. Doesn't matter. The goal is to decide who to APPROACH with the book. Who will BUY the book, and for what line. Don't worry about the little stuff.
If you've built a world, and you have magic involved, it qualifies for fantasy. Heck, if you've built a world, and it only has vampires, it's still fine, because there's some element of magic involved in being able to turn into a bat, or dissolve into mist, etc., etc.
Make sense?
. Any thoughts on this topic would be appreciated! 
Dark fantasy, maybe? What did they tell you over on the HWA board?
Boy, I've never heard THAT! Laurell is a member of HWA, and HER books are dark fantasy (or at least that's what the publisher markets them as!) I know, because I looked when trying to find a home for our vampire series that's similar to hers -- the one that's pictured to the left. (We wound up increasing the romance to publish it with Tor's paranormal romance line, but second in queue was dark fantasy.)
