A Spirit is a personification of something and they generally highly dislike bring confused with ghosts. A few fae  (nymphys, sylphs, niads, etc) as well as elementals fall into this but they're generally weaker than the personifications of 'ideas' and 'beliefs' like the Phoenix, Spirit of Reincarnation or such. They are created to represent that or are stayed as the thing they're to represent us. As in, one might form just from thoughts of many people or one may be chosen to represent a dying belief or to be that belief given form. They often work under the Deity of what they represent. If a Deity is the teacher, Spirits are the TAs.

A Celestial is like a deity but not as strong except that DemiCelestials aren't as weak as DemiDeities (they're still pretty weak but they're immortal as long as they take care of what their bodies need) and actually have the potential to reach their parent's level without a gift of god power.  I've actually read a lot of stories none of them published though and basically some universes have celestials and others have deities and it's rare for them to be together in the same universe but it's happened before and celestials are kind of like the substitute teacher if the deities are the teachers. Another thing, the celestials are like a cross between a spirit and a deity. Basically, the Celestial can actually become stronger than the deity if not already and it's both a personification and a controller. Celestials start out weaker but they can definitely get pretty damn strong. They're basically pretty close to a Deity just weaker in some areas and stronger in others. If a Deity is a teacher, Celestials are Substitute Teachers

A Deity is a powerful entity in its own right though their demideity children aren't very strong. There isn't much to say about them because most people already understand what they are. They live on a higher Heavenly Plane than the Celestials. They would probably be the teacher in terms of rank.

The Ancients are Deities that may no longer exist for one reason or another. Some Deities fade in and out and may eventually lose what they present or they just grow so old that others replace them, like an apprenticeship. They're the ones who taught the teachers and will continue to do so until they're gone. As long as their domain exists anywhere, they will live, even if 'sickly' from lack of worship.

Creator deities are the most powerful entities within their dimension. They filled out and thus as like as their dimension thrives they will survive. However, dimensions do eventually die, but the deities won't die immediately because of the memories of those who had been there. Should are usually naps by credit Deities but some Creators gave a domain of soul creation to other Deities. Souls created by a Creator are usually bound to that dimension but those created by someone else or with the aid of someone from a different dimension can go to different dimensions and continue on even after that one has gone, their memories serving as worship enough to keep the Creator going.

Originals are the most powerful entities within their reality. There are nine of them per reality and can be labeled as the nine character archetypes if one so wishes. They all represent something similar in each reality. The lawful good embodiment of Life, the neutral good embodiment of all that is Good, the chaotic good embodiment of Light. The lawful neutral embodiment of Karma, the true neutral embodiment of Time, the chaotic neutral embodiment of Magick. The lawful 'evil' embodiment of Death, The neutral evil embodiment of all that is Evil, the chaotic 'evil' embodiment of Darkness. If a Deity is a teacher, they're the principal or school board.