head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Optimization · Pure Optimization
A pure loot-and-build treadmill where set-bonus optimisation and Rift pushing define performance.

Optimization · Pure Optimization
An ARPG where build crafting and skill trees define success.
Diablo III leans Optimization (Pure Optimization); Last Epoch leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo III
Greater Rift pushing has minor mechanical demand in builds
Last Epoch
Action combat, modest mechanical demands
Diablo III leans a little harder on reads, though the gap is small.
Diablo III
No meaningful adaptive opponent; co-op is cooperative
Last Epoch
No adaptive opponents
Diablo III leans a little harder on variance, though the gap is small.
Diablo III
Primal Ancient drops and set dungeon RNG drive the grind
Last Epoch
Loot affixes and crafting outcomes vary
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo III
Set bonuses and paragon levelling are almost entirely solvable
Last Epoch
Build planning is the entire game
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.