i propose a simple distinction between these non-material entities: 
- demons violate natural law thru obfuscation, deception, and coercion; demons work thru weak men;
- ghosts are energy fields of souls that have passed on but have unfinished business in the material world; ghosts do not violate natural law, but are usually not helpful - they are the astral NPC's;
- angels are the energy fields of true/truth creation - they respect, follow, and teach natural law; 