head to head
Divinity: Original Sin 2 asks more than Diablo II, and the gap is reads.

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

Optimization · Pure Optimization
A deeply optimizable tactical RPG where armor stripping and initiative manipulation produce near-deterministic victories.
Diablo II leans Optimization (Pure Optimization); Divinity: Original Sin 2 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
Divinity: Original Sin 2
Turn-based system demands zero reaction speed or motor precision
Divinity: Original Sin 2 leans clearly harder on reads.
Diablo II
Monster AI is fully mappable
Divinity: Original Sin 2
Multiplayer PvP arena adds light opponent-reading; solo is scripted
Diablo II leans a little harder on variance, though the gap is small.
Diablo II
Loot RNG and random maps drive the grind
Divinity: Original Sin 2
Source point limits and hidden enemy armor values create unknowns
Divinity: Original Sin 2 leans a little harder on optimization, though the gap is small.
Diablo II
Builds, breakpoints, rune economy, magic-find routing are the game
Divinity: Original Sin 2
Lone Wolf builds and damage-type stacking define solved optimal strategies
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.