Go for it, Setanta.
There appears to be quite a bit of over-lap between the two.
Yes, i'd say there is. The Once and Future King
would qualify as fantasy which is not science fiction. (The title comes from Thomas Mallory's Mort d'Arthur
--first printed by Caxton in 1485, it's the first "best seller" printed in English. Mallory states the the inscription on Arthur's tomb was Hic iacet Arturus, Rex quandum, Rexque futurus
--Here lies Arthur, once and guture King.) In the King Arthur line, there are just a heap of books, many of which are multi-volume sets, and many of which, perhaps most of which are not worth the paper they are printed on.
The Mists of Avalon
is an excellent example of this genre, though. It's by Marion Zimmer Bradley, a doyenne of the fantasy genre. A rather palid television miniseries was made from the book.
One fantasy series of novels and short stories which straddles the line between science fiction and fantasy is the Dragonriders of Pern series by Anne McCaffrey. She is also one of the giants of fantasy literature, and has written some books with Marion Zimmer Bradley, and with other fantasy fiction, female authors. The Dragonriders series is just enormous, literally dozens of novels and short stoies, and her son, Todd McCaffrey has continued the series in this centurry. Look her up to get a list of all the novels and short stories.
There is a game series of which you may have heard called Dungeons and Dragons. About the most popular setting for these games is Faerûn, a mythical planet populated by creatures which occur in D & D, greatly inspired by J.R.R. Tolkien (orcs and hobbits in addition to various forms of elves, gnomes, goblins, etc.--there are humanoid races, being humans, elves and half-elves [a human-elf crossbreed], dwarves and giants; then there aer goblinoid races, beign orcs, goblins, hobgoblins, ogres, etc.--dark elves and dark dwarves represent just more variations on the basic themes).
These "Forgotten Realms" games have inspired a series of novels, of which there are literally dozens. Both the games and the novles are very popular.