A spirit is any non corporeal entity that can be interacted with by material creatures.
There are many types of spirits, so let’s go…
Demons: typically chthonic or terrestrially inclined spirits allied with a more chaotic neutral current. Though, some can have celestial aspects or qualities.
Angels: A group of celestial and planetary spirits that serve the creator entity, who is not Yahweh. They tend to be more, functionary entities that work in their particular offices more rigidly. They are still very helpful to human beings, regardless of their religion.
The dead: NOT “undead”. These are just the spirits of dead physical creatures. Human, animal, plant, etc. The most useful tend to be dead animals, particularly humans. They are hot, chthonic spirits and should only be worked with by those of sound mind and intelligence.
Saints: These are enlightened dead folk, who have achieved more power in the world of the dead thanks to religious rites performed for them and cults that pay them veneration. They are far more accessible than the ordinary dead and each have their own specialty. They are very similar to, and can be considered the same as at times, enlightened ancestors. Though, some saints are actually masks for pagan gods and are not dead at all.
Ancestors: these are dead folk in your family line, or other dead folk you adopt into your court. They are the closest spirits in your life and will help you in anything you want or need, so long as they agree with it. They should be prayed for and venerated for them to grow stronger…because remember, you too will join them someday.
Deities: Aka gods, pagan gods, etc. These entities can criss cross with angels, demons, and saints, using these forms to continue their agenda and worship. For example, The goddess Astarte is the demon Astaroth. The Celtic goddess Brigid is St Brigid. Gods are basically really powerful entities that are above everything I’ve listed so far. They are also typically more removed from our plane as a result. Think of it like an onion, angels and demons exist on layers closer to the core (our material world) and gods live on layers further away. Which could be one of many reasons why some have chosen to appear as demons, etc.
Land spirits: these are spirits who live in the land itself. They are genii of rivers, seas, lakes, crossroads, trees, plants. Etc. Some are even dead folk who were ritually sacrificed and their spirit tied to the land. They are everywhere and are some the closest entities to our physical world, as many have physical anchors in the shape of mountains, roads, etc. Where they live, the history of the land, etc. Can determine what kind of spirit that they are and the r temperament. For example, I met some land spirits in a rural area in my county, and they were very angry about the state of their wilderness being desecrated by humans. While the spirits in my urban city are far less angry and more used to human activity. They criss cross with fairies and elementals.
There are many many more, but they tend to be mixes or similar concepts to what I’ve given above.