Spirit plane

The spirit plane and the material plane are closely related, yet very different. The spirit plane, for instance, has no strict topography. The most popular analogy among those who travel there is "swimming in a constantly stirring soup". Though some spirits, mostly elemental, seem to hold their ground and give a sense of order. As in our world the inhabitants of the spirit plane are numerous and versatile. There are no strict rules when it comes to spirits, but we can try and sort them into these four categories.

life spirits are spirits of plants and animals. It rarely happens that a spirit is a counterpart of a single animal or plant, but rather a whole pack, flock, forest etc. They have influence over their material counterpart, thus shamans bargain with them for help in the material plane. As nothing is set in stone in the spirit plane a single spirit can be a counterpart for one animal/plant, or they can have no living counterpart.

ghosts are spirits of the lost, punished, mad. In some tales they are bur parts of a spirit. Ghosts almost never have living counterparts. They are mostly considered evil, doing whatever necessary to fulfill their mysterious agendas. In folk tales they are often the antagonist, trying to trick the hero in to possessing his body.

elemental spirits almost always have counterparts in the material plane. Mountain spirits have mountains, spirits have river etc. Some spirits have counterparts only some times, for instance storm spirits. Elemental spirits are hard to understand and communicate with but a shaman with such talents is considered very wise and powerful.

folken spirits are spirits of sentient beings, self aware enough to pretty much stay the same person even after death. They rarely linger in the spirit realm long, but travel wherever afterlife the gods deem them worthy of.

Again, these are very flexible definition. There are records of spirits belonging to more than one of these groups, even some not belonging to any. Dream walkers should always be on their guard and never assume.