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

Optimization · Pure Optimization
The genre-defining loot ARPG whose builds, runes, and trade economy players still optimize decades later.

Optimization · Pure Optimization
A theorycraft-dense ARPG about engineering builds through randomised loot and crafting.
Diablo II leans Optimization (Pure Optimization); Path of Exile leans Optimization (Pure Optimization).
Path of Exile leans a little harder on execution, though the gap is small.
Diablo II
Positioning and potion reflexes, little else physical
Path of Exile
Some dodge and reflex play, but build carries fights.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo II
Monster AI is fully mappable
Path of Exile
Mobs and bosses are scripted; no adaptation.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo II
Loot RNG and random maps drive the grind
Path of Exile
Loot, map mods, and crafting outcomes are heavily random.
Path of Exile leans a little harder on optimization, though the gap is small.
Diablo II
Builds, breakpoints, rune economy, magic-find routing are the game
Path of Exile
Passive tree, crafting, and economy form near-infinite theorycraft.
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.