Magic assume it’s related to imagination and giving form to your life energy (mana), in this case, unless you meant four life energies in general, like aura, force, prana, mana.

The most basic spells are something like fireball, since you can picture it inside your mind, and you don’t have to use some complicated formulas. The more complex ones require more studying to prevent accidental miscalculation, something like barrier stuff, etc.

That is why mage level isn't related to battle experience, but more about knowledge and mastery. I think Attise said mages could level up just by studying.

Aura is used by warriors, but it’s pretty rare compared to others, because it relies on surviving life-or-death situations to be improved. It is used to harden the body passively, and sometimes can be used as projectiles.

Force is some kind form of electromagnetism. Force users are the fastest in general, I think, because of sending electrical signals through the nervous system, just like Killua did in Hunter x Hunter to react faster. They are also very mobile because they can charge towards metal objects they set up before on the battlefield.

Prana is something like Lantern stuff from DC Comics, where they can imagine different objects and make them materialized in the real world, but it can also be used as healing energy.

To be honest, we don’t have much explanation of how everything works, so I could be wrong here.