Spirit

Spirits are residual Cosmic Energy left from the dead. Most of the spirits are invisible and silent, but some become visible due to various reasons. Most types of Spirit can inflict physical wounds and can interact with physical objects when they become visible, but Spirits cannot be touched or be wounded by physical beings. Spirits can also decide if they are visible or not.

Souls
In regular circumstances every dead should only be a regular soul resting for a few decades, moving and hearing the living that try to communicate with them, until they fade into nothing.

Ghost
Ghosts are tied to their remains and await some proper funeral rites in order to start fading. They beg for those they cross to help them go to rest.

Guardian
Guardians are tied to someone, a place or an object, that they promised to protect in life or in death. They are tied to what they protect until it no longer needs protection and then the Guardian then start to fade. Guardians only appear when their protection is really needed and will use anything at their disposal to accomplish their task.

Specter
Specters do not fade due to unfinished business. People that made a sacred promise that they had to accomplish "in this life or the next", will rise up from their grave after their death and wander to fulfill their promise. They are harmless to those who help them but can attack those who refuse to help or try to stop them. Specters will become regular Souls and start fading when they have fulfilled their promise.

Wraith
Wraiths are do not fade due to a particularity horrible death. They rise up from their grave wander searching for revenge and do not hesitate to attack on sight. Wraiths will become regular Souls and start fading when they are avenged.

Angel
Angels travel around the world guiding lost souls. Only the most pure and benevolent individuals become Angels having sacrificed their needs and desires to help those in need.

Demon
Demons do not fade of their own will to continue the torture of living beings. Only the most evil individuals become Demons, getting their only pleasure and satisfaction in the blood and suffering of the others. They roam free to torment weak individuals. They find hosts that will be easily manipulated and make them have visions and hear voices until they start mutilating themselves and attacking their friends. Once a host is dead the demon searches for another host. The only way to stop a demon is to trap it until it decides to fade on its own.