In a haunted house, the evil spirits must be warded off/chased away.
Which one would be the better choice? Do they mean the same?
"Warding something off" is a more defensive act than "chasing them away", which can be regarded as offensive. To ward off an evil spirit, you need only keep that spirit at bay, and avoid being affected by it. For example, wearing a garlic necklace and carrying a cross might ward off a vampire, but it usually doesn't chase them away (at least in the movies it doesn't)