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 · Systems & Chaos
An ARPG loot grind about chasing affix rolls to feed a damage-stack build.

Variance · Systems & Chaos
Managing a manual-aim shooting layer on top of XCOM-style strategic campaign optimization.
Diablo IV leans Optimization (Systems & Chaos); Phoenix Point leans Variance (Systems & Chaos).
Phoenix Point leans a little harder on execution, though the gap is small.
Diablo IV
Clicking and dodging are light; gear carries you.
Phoenix Point
Manual aiming system introduces real accuracy input on every shot
Phoenix Point leans a little harder on reads, though the gap is small.
Diablo IV
Enemies and bosses are scripted; no adaptive opponent.
Phoenix Point
Alien factions evolve threat pools but not adaptively against you personally
Phoenix Point leans a little harder on variance, though the gap is small.
Diablo IV
Loot rolls, affixes, and uniques drive every session.
Phoenix Point
Body-part hit location and mutation pools drive heavy RNG swings
Diablo IV leans a little harder on optimization, though the gap is small.
Diablo IV
Paragon, aspects, and damage buckets are solvable theorycraft.
Phoenix Point
Research priority, vehicle builds, and faction balance are deeply optimizable
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.