Imo celestial bodies are classified into major categories based on their mass.
- Stars: these objects are massive enough to achieve hydrogen fusion, or used to.
- Brown dwarfs: massive enough to achieve some kind of fusion, but not hydrogen fusion.
- Planets: not massive enough to achieve any sort of fusion on its own, but is massive enough to be in hydrostatic equilibrium.
- Planetoids: not massive enough to be in hydrostatic equilibrium, but features some geological activity.
- Asteroids: not massive enough to be in hydrostatic equilibrium, and no geological activity.
Then, you separate each of them into various subcategories:
- Stars
--- Normal stars
----- Hypergiants
----- Supergiants
----- Bright giants
----- Giants
----- Subgiants
----- Main sequence stars (dwarfs)
----- Subdwarfs
--- Degenerate stars
----- White dwarfs
----- Neutron stars
------- Pulsars
----- Black holes
----- other types of dense stars
- Brown dwarfs
- Planets
--- Major planets
----- Gas planets [subcategories based on dominant component]
------- Gas giants [subcategories based on mass]
--------- Super Jupiters
--------- Jupiters
--------- Saturnians
--------- Gas dwarfs
------- Ice giants (mostly volatiles, with substantial hydrogen/helium envelope))
------- Rock giants (mostly rocky, with substantial hydrogen/helium envelope)
----- Ice planets / ocean planets (mostly volatiles, with no substantial hydrogen/helium envelope)
------- (shit ton of subcategories)
----- Rocky planets
------- (shit ton of subcategories here as well)
--- Satellite planets
----- (the same as major planets)
- Planetoids
--- (too lazy to write it down)
- Asteroids
--- (the current classification seems fine)
There is also another system for gas planets, ice planets, and Venusians which is based on the planet's temperature, but that one gets complex fast. Sudarsky classification doesn't cover them all.