head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Optimization · Pure Optimization
An open-world shooter-RPG won by perk routing and weapon mod optimization.

Optimization · Practiced Mastery
An RPG where preparation, alchemy, and build choices outweigh raw combat reflexes.
Fallout 4 leans Optimization (Pure Optimization); The Witcher 2: Assassins of Kings - Enhanced Edition leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 4
FPS aiming, VATS softens demand
The Witcher 2: Assassins of Kings - Enhanced Edition
combat timing and dodges matter
Fallout 4 leans a little harder on reads, though the gap is small.
Fallout 4
Scripted enemy AI
The Witcher 2: Assassins of Kings - Enhanced Edition
scripted monster and human AI
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 4
Loot and legendary rolls
The Witcher 2: Assassins of Kings - Enhanced Edition
alchemy and loot drops vary
Fallout 4 leans a little harder on optimization, though the gap is small.
Fallout 4
Perks, settlement, weapon mod planning
The Witcher 2: Assassins of Kings - Enhanced Edition
builds and preparation are solvable
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.