There are two main types of hauntings: the residual haunting and the intelligent haunting. They differ greatly.
A residual haunting is a playback of a past event. This may be in the form of visual, auditory or olfactory evidence. The ghosts involved are not aware of the living world around them and cannot interact with the living world. These types of hauntings usually occur when an extreme or traumatic event took place in a certain area or building. These places then store the massive and sudden outburst of energy and playback the event repeatedly. Apparitions in these hauntings will repeat the same path or activity over and over again, not hindered by humans or materials around it. Other activity that is associated with these types of hauntings are disembodied voices, anomalous sounds and smells. A residual haunting has no interactive spirits, but is made up of left over and accumulated energy creating and replaying sounds, smells and apparitions of people and things of the past.
An intelligent haunting is one where the spirit/entity is aware of the us and it's environment and can intelligently interact with the us and the environment. Spirits of intelligent hauntings are able to communicate directly with us, answering questions and responding to cues and actions made by investigators and humans. These hauntings generally occur in a place a spirit is attached to(ex- place of death, well known spot in the spirits life, etc) or where a spirit has become attached. They occur when a spirit builds up enough energy to be able to manifest itself. Other activity associated with this type of haunting include the moving of objects, anomalous sounds, EVPs, EMF spikes and more.