Interesting thread. Over the past few years, I have been reading and re-reading a lot of stuff on this and related topics. What I have learned is that not all supernatural manifestations are the same thing. Do ghosts exist? Yes. Do demons exist? Yes. Are there both lesser and greater demons? Yes. How they manifest themselves is quite different.
Ghosts are the spirits of deceased human beings, which for whatever reason have not passed over to the "other side". They may not want to leave familiar, comforting surroundings, or perhaps they're afraid of meeting their Maker; sometimes they hang around because they have unfinished business, or a lot of times they're simply confused about what's happened and they don't know
how to get to the other side. They can manifest by appearing as gauzy apparitions, as a chilly feeling, or as light electrical sensations in the atmosphere. In rare cases, they may be able to create small noises, but not terribly often---they don't have the ability to draw enough energy to do that.
Demons, on the other hand, are spirits who have never walked the earth in human form; in fact, they pre-date the human race. They can manifest themselves in ways that range from a mild "creepy" feeling in a house or room all the way up to levitating extremely heavy objects such as refrigerators or chests of bureau drawers and hurling them across rooms. They are known for smashing pictures on walls, causing foul-smelling gunk to leak out of walls and ceilings, and other manifestations like screams, shouts, moans, smells like sulphur or fire or excrement; they can appear as all manner of strange and frightening creatures, and they can and do inflict actual physical damage on human beings. There are many cases of people being punched, scratched, lifted off beds and hurled to the floor, thrown across rooms, and even sexually raped by demonic entities.
Naturally, such cases that get that bad only get that way because the dumb human beings opened a door somehow to allow them to enter; kids playing with Ouija boards is a common portal for entrance, although messing around with spell-casting or Tarot cards or séances will do it, too, as will stubborn persistence is some kind of sinful activity.
Demonic entities feed off all kinds of energy to grow strong enough to cause physical manifestation; they can suck the heat out of a room in seconds, leaving it icy cold even in a sweltering August heat wave; they can absorb ambient electrical energy from things like thunderstorms; but what they really feed upon are emotional fuels such as hate and rage and especially fear. If they can scare the bejabbers out of the people living in an infested house, they can absorb that powerful energy and use it to create no end of malignant mischief.
I could go on, but what it boils down to is that ghosts and demons ain't the same breed of cat. I can give you list of very good books on the topic if you're interested.
But the main thing I'd advise is that we all remain just as close to the Good Lord as we can, because trust me, from what I have studied, this type of stuff is not something anybody wants to get tangled up in.
