For some reason, I've been running across people who imagine that the folklore is all clear and distinct between fairies and ghosts.
Sometimes it's quick to clear up. Like a time someone said that a rusalka looked like a ghost, not a fairy, and I cleared up the point: the rusalki were water spirits from drowned maidens.
Others declare that while the -- ehem -- Good Folk might take you away for an afternoon that proves to be a century, like Rip van Winkle, Rip van Winkle himself was actually the victim of the ghosts of Henry Hudson and his crew, which is obviously different. Or the declaration that despite modern presentations of them as the undead, the bean sidhe (or banshee) was actually a fairy. Now, while the very name bean sidhe means fairy woman, it was indeed often a ghost in folklore. So were various brownie figures. There was a fuzzy borderline, because of course some people only apparently die, being in reality taken by the Good Folk while a stock was left in their place, but a good number are clearly and definitely the dead. It's not for nothing that the King of Faerie features in Sir Orfeo in Hades's place in the tale.