Considering how the ursuper from the 18th floor had 4 big ulti skills that caused quite the problem for MC and that those 4 things were then portrayed as those divinity orbs, I guess is that those orbs are something more like fragments or the potential of divinities instead of actual essence of absolute 'divinity' that the gods have over their field. While still quite strong and often fatal against ones enemies, they are weaker than the original, pure form of the divinity that their respective god had and used. My guess is that those orbs are the result of some weird synergy effect between the systematics behind his necromancy skill and that skill that allows him to absorb or eat relics and other stuff with divinity in it, but it's all just guesses, so take it with a few grains of salt.

Maybe there's a difference in them. He was god and our mc is not and plus he has that unlocked skill & divinity