Demons, however, are always associated with being a dark presence. One that can make people feel uneasy, and are thought to be able to present actual physical harm.

The main difference between a ghost and a demon is that ghosts are thought to be the lingering spirit of a human being that once walked this earth. It is not known where demons come from, but they are not believed to have ever been of human origin.
If you believe your home is haunted, and want to know if you have ghostly or demonic presence, you will need to understand the differences between how the two behave.
Most ghost type haunts fall into two main categories: intelligent and residual. An intelligent haunting is one in which the spirit is able to react and connect in different ways. A residual haunt is when a spirit replays the same scenario within a location over and over. They are not aware of the people around them, and no not try to make contact. The line between an intelligent haunt and demon presence can be blurred, as human contact can be made in both cases. However, the contact of a demon is typically malicious in nature. Some believe that this is because demons are envious of those that have a human body.
The main method that demons use to cause harm is through causing disturbances that cause individuals to live in fear. However, there have been reports of people being scratched, hit, and otherwise injured at the hands of a malicious demon.

If any of these things have taken place within your home, chances are, you are dealing with a demon, and not a ghost.
Similar to ghosts, demon voices can be captured on tape. They are not immune to electronic voice phenomenon capturing methods. There is a difference, however, in the type of voice or sound that is typically captured. Demon voices are menacing, and usually quite clear in their message. They have also been known to produce low guttural growls. Capturing these type of sounds can be quite a terrifying experience for a homeowner, but is a good way to quickly get to the bottom of which type of entity is residing within the home.
Demons and ghosts alike can be asked to leave the home. This does not always work, but if you are bothered by a presence, it is the first step. Demons are infamous for not always leaving when asked, as they seem to be drawn to human energy. Other methods, such as a house cleansing would be the next step. Often, this provides at least temporary relief, and can solve the problem altogether.

Source: voices.yahoo.com