Ghost is a creature of hell that do not get eternal satisfaction. According to different religion and legends, spirits which become ghosts are different. Dead bodies which are not cremated or buried properly turn into ghost. Many spirits roam for revenge due to untimely killing.
Ghosts,witches,chudail,pret,demons,devils,pan-doobbi - names may be different. But, All implies only one- Wandering spirits.
Scary things about ghosts
Also read - Haunted kasara ghat in nashik