Demons can be seen under different names through all of history and in many different beliefs. Some of the 'angels' are just demons that scared rhp practicioners work with under a different name so that they don't practice 'dark' magick. Imposter spirits act like they are a different spirit, most of the time a higher spirit like a demon. When they act like they're demons they get punished fairly quick tho. There's no real name for spirits that act like a non existing higher being but they're of the same origin as imposter spirits. They do it for the same reasons - to drain your energy and inflict harm on you. Many angels are just these spirits, that's why they fuck things up so much.