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 · Practiced Mastery
The first Dishonored: a stealth-action playground of layered powers.

Optimization · Pure Optimization
An open-world shooter-RPG won by perk routing and weapon mod optimization.
Dishonored leans Optimization (Practiced Mastery); Fallout 4 leans Optimization (Pure Optimization).
Dishonored leans a little harder on execution, though the gap is small.
Dishonored
Blink timing and combat inputs matter.
Fallout 4
FPS aiming, VATS softens demand
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dishonored
Guard AI scripted, non-adaptive.
Fallout 4
Scripted enemy AI
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dishonored
Patrol timings vary mildly.
Fallout 4
Loot and legendary rolls
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dishonored
Power combos and stealth routes solvable.
Fallout 4
Perks, settlement, weapon mod 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.