What’s the difference between Ascended, Aspects, Freljordian demigods, Aurelian Sol, and whatever Soraka’s got going on? Are they all just different varieties of League gods?
Hoo boy, okay, so. First of all, Riot have been pretty adamant that there are no gods in Runeterra, every god-like being that exists in that universe is actually a spirit or just a very powerful being of some kind, but definitely no real gods, no matter how much it seems like they are definitely writing these characters to be actual literal gods.
I don't 100% know why they are so insistent on this, but I imagine it has something to do with censorship and ratings agencies, or maybe they just don't want to have to establish any actual theology on Runeterra. Volibear isn't the god of storms for real, he's just a super powerful spirit that can create storms in the Freljord, but not all of them, so please don't ask us whether every single thunderstorm in the Freljord was something he did deliberately. That sort of vibe.
To go through them point by point:
Celestials & Aspects
The Celestials are beings like Aurelion Sol and Bard, which exist as cosmic entities operating on levels of power and motivation beyond human understanding. They came into existence with the universe itself, and tend to busy themselves governing various parts of its operation. They are, again not gods (Riot is very insistent on this), but Aurelion Sol literally made every star in the galaxy, he's functionally the progenitor god of Creation.
Some of them, though, like to interfere in the mortal world of Runetera in various ways, and they tend to use mortal vessels to do it. That's where we get Aspects: Aspects are mortals who are chosen by the Celestials that live on Mount Targon to contain their power and be their avatars in the mortal world.
Leona is the Aspect of a Sun celestial, Diana of the Moon celestial, Pantheon is the Aspect of War (or he was, until Aatrox killed it, but he retains access to many of its powers), and Zoe is the Aspect of Twilight, and so on.
Soraka is another Celestial in mortal form, but she is NOT an Ascended. Rather than possess a mortal, she created a mortal body for herself and poured the whole of her being into it, which is causing her body to permanently burn up from the inside while she regenerates it with her magic. She lives on Runeterra and acts as a mysterious mystical wise guide and mentor to mortals who need it.
Ascended & Darkin
Ascended are somewhat similar in kind to the Aspects, but usually lesser in power. The Ascended are also human beings infused with Celestial magic and power, specifically with the power of the Sun, although as far as I know, that power is drawn not from the Celestial of the Sun who empowers Leona, but directly from the physical Sun itself. This means the Ascended aren't possessed by Celestials and retain full free will, at the cost (or let's be real: benefit) of being transformed into furries, which extremely coincidentally just so happen to closely resemble the gods of the Egyptian pantheon. but again, they are definitely not gods, please don't put it in the newspaper that they are gods.
I don't know exactly how canon Riot considers this anymore, but the lore was that the Aspects of Mount Targon gifted the power of Ascension to Shurima in order to produce Ascended that could serve as shock-troops in the war against the Void, which is a swarm of extradimensional horrors that are constantly trying to eat the world. Whatever the case, the Ascended DID fight the Void, and it traumatized and corrupted them so badly that they degenerated into body-horror blood monsters called the Darkin.
The Darkin fell into civil war and it got so bad that The Aspect of Twilight (not Zoe but her predecessor in the role) decided to use some magical trickery to imprison them all in their weapons, which is where they've stayed for a few thousand years, getting even more traumatized and mentally destabilized by the total sensory deprivation and solitary confinement. If any mortal touches a Darkin weapon, it immediately assimilates them and uses their flesh as a new host, and then goes on a killing rampage about it. That's where you get your Aatrox, your Varus and (eventually, once he devours Kayn) your Rhaast.
Gods, Spirits & Demons
This is the category for Ornn, Anivia, Volibear, The Seal Sister and so on. The Freljordian people worship them as gods, but they are, technically, only extremely powerful nature spirits, manifestations of the nature of the Freljord itself, which draw power from the land and to a lesser extent from their worshipers. There are many, many lesser nature spirits, which might be worshiped as gods by particular tribes or hold power over particular areas, but Ornn, Anivia, Volibear, The Seal Sister and the Iron Boar are the most powerful and most widely revered.
On a similar note, Ionia is absolutely choked to the gills with spirits, because those lands are soaked in magic. They are usually not worshiped as gods specifically, but take the shape of everything from dragons to living trees to sprites and will-o-wisps and which roam fairly freely in Ionia. This includes characters like Lillia, who is the daughter of a magical tree of dreams on whose branches the dreams of mortals grow and mature, and it includes Ivern, who is an extremely powerful and ancient nature spirit formed from the soul of a magical tree.
Demons are distinct from spirits, in that rather than drawing on the power of the land or fountains of magic, they draw on the emotions of living things for their powers. The most powerful demons are known as The Ten, who get their power from the most primal emotions that living things feel. Fiddlesticks is the demon of Fear, and Nilah somehow draws her strength from Ashlesh, the Demon of Joy, whom her order has imprisoned. We don't know who the rest of the Ten are yet, but Riot seems to have that worked out somewhere in their internal deep lore.
Swain has a lesser (but still powerful) demon of secrets called Raum bound in his arm through some sort of deal, Evelynn is a demon of anguish and pain, Tahm Kench is a demon of addiction, and Nocturne is a demon of nightmares.
Besides those, there are an untold number of lesser demons, who feed on more and more specific feelings, and thus are less and less powerful because there's simply less of that stuff around to feed on. They are often called Azakana, and may be demons that feed on feelings as niche as, like, noblemen's fear of their extramarital affairs with handsome commoners being discovered. Yone hunts the Azakana and collects their mask, although even he doesn't know quite what for.
Death
This is where we place the Kindred. Technically they are merely Spirits of Death, but more than perhaps any other category of creature, Riot keeps writing them as Literal Gods of death and I don't think it makes sense to think of them any other way.
The Kindred take on many different shapes all across Runeterra, seemingly influenced in large part by the expectations of the people or creatures who are dying, but their most popular visage is that of a Lamb and a Wolf, hunting together. Lamb's merciful arrow ends your life if you accept that your time is up and go gently into that good night, but Wolf hunts you down and rips you to shreds if you resist and fight to your last breath, destiny be damned.
The Kindred are there for every death on Runeterra, they are the mediators (as far as we know) of all forms of death everywhere, and by far the most classically "anthropomorphic embodiment of universal existence" style god in the lore that we know of. Where a god like Anivia only really has power in the Freljord, the Kindred have power everywhere there is life. Only the undead escape them, and even then, only temporarily.
In Conclusion
YES Runeterra has tons of gods, it obviously has gods, you can't walk five feet in that universe without tripping on a god, but they tend to be gods with hard limitations on their power and influence, and rarely have powers on the level of bending reality itself.
Even Aurelion Sol, who literally makes stars, can't snap his fingers and undo causality, for example, or suspend the laws of physics wholesale.
Riot's weird insistence on "no gods in Runeterra" is more of an affectation, a bit of a put-on, than an actual narrative principle, and most of the gods of Runeterra can be understood very comfortably through the lens of various non-Christian religions like Norse or Greek mythology, or the hero/god characters of something like Polynesian myth.
