So what is the difference between Socerer kings of Athas and those true gods?It's not just "power" and "book knowledge", it is a deeper and more fuller understanding of the Cosmos, Creation, Life, Death and Everything. A 1st level wizard and a 20th level wizard both still point a finger and cast a spell, levels does not bring understanding, wisdom or anything else.
They possess immense power, far surpassing the vast majority of mortals.
They are immortal.
They are able to bestow various divine spells to their servants.
They can decide the treatment of their subjects after death————of course, they actually cannot, but they make their subjects believe they can through carefully crafted and constantly patched lies.
So they are no different from real gods, they just relatively weak.