head to head
The First Descendant asks more than Diablo III, and the gap is execution.

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

Optimization · Practiced Mastery
A co-op third-person looter shooter where module build optimisation and drop variance define long-term progression.
Diablo III leans Optimization (Pure Optimization); The First Descendant leans Optimization (Practiced Mastery).
The First Descendant leans clearly harder on execution.
Diablo III
Greater Rift pushing has minor mechanical demand in builds
The First Descendant
Colossus boss fights and intercept missions require dodge timing and aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo III
No meaningful adaptive opponent; co-op is cooperative
The First Descendant
PvE co-op throughout with no meaningful adaptive opponent
The First Descendant leans a little harder on variance, though the gap is small.
Diablo III
Primal Ancient drops and set dungeon RNG drive the grind
The First Descendant
Module drop RNG and Descendant unlock rates drive the grind
Diablo III leans a little harder on optimization, though the gap is small.
Diablo III
Set bonuses and paragon levelling are almost entirely solvable
The First Descendant
Module builds and Descendant loadouts are extensively theory-crafted
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.