When living beings in IDET die, they become ghosts or undead.
They have no life force in common, but instead possess ghostly qualities and are transported by some means to a place called Enendepete, where their presence is unrecognizable to all but a few living beings. (*Ghostly qualities are special powers that only the dead possess.)
They have few desires and needs in common, especially the need to sleep, eat, or procreate as living beings do, and they are mentally stable with few emotional upsets.
They work under the umbrella of the God of Death, and only a few individuals with unusual characteristics are given powerful positions.
To summarize the difference between ghosts and the undead, a ghost is a being that has died and become a soul, while the undead are ghostly forces that reside in a corpse.
Ghosts are not physically present and can pass through all objects, and only those with ghostly powers can come into contact with them. Most of their outward appearance is that of their life before death.
The undead are corpses, so they are physically present and can act on their own, but they have very low intelligence.