ghosts are dead spirits of actual people, incorporeal but occasionally able to physically manipulate their surroundings or possess people. ghouls are their own species/monster that is bestial and eats the flesh and bones of the dead. think Pickman's Model or the Night People from Ringworld. vaguely canine, intelligent, sometimes used to be people who just fell in with a bad crowd, a la Pickman's Model again or The Graveyard Book. I like ghouls :B