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 · Pure Optimization
A VATS-heavy wasteland RPG won by perk and build optimization.

Optimization · Pure Optimization
Immersive sim aboard Talos I where build and route choices dominate.
Fallout 3 leans Optimization (Pure Optimization); Prey (2017) leans Optimization (Pure Optimization).
Prey (2017) leans a little harder on execution, though the gap is small.
Fallout 3
VATS-leaning combat, low aim demand
Prey (2017)
Wrench and Gloo timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 3
Scripted enemies
Prey (2017)
Typhon AI scripted, not adaptive.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout 3
Loot rolls, SPECIAL checks
Prey (2017)
Mimics and resource spawns randomized.
Prey (2017) leans a little harder on optimization, though the gap is small.
Fallout 3
Perk and build planning carries the run
Prey (2017)
Neuromods, builds, station routing deeply 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.