head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, 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 party-based loot ARPG marching a customizable squad across Aranna against Valdis.
Diablo II leans Optimization (Pure Optimization); Dungeon Siege II 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 II
Positioning and potion reflexes, little else physical
Dungeon Siege II
Party combat mostly automates itself
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
Dungeon Siege II
Enemies follow simple scripts
Diablo II leans a little harder on variance, though the gap is small.
Diablo II
Loot RNG and random maps drive the grind
Dungeon Siege II
Random loot and chant rewards
Diablo II leans a little harder on optimization, though the gap is small.
Diablo II
Builds, breakpoints, rune economy, magic-find routing are the game
Dungeon Siege II
Party composition, pet raising, skill tree planning
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.