head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Practiced Mastery
Routing scripted patrols with vampire teleports and a light skill-build layer.

Optimization · Practiced Mastery
An accessible action RPG of moral choices, property empires, and a loyal dog.
Dark leans Optimization (Practiced Mastery); Fable II 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.
Dark
Shadow-teleport timing matters but combat is clunky-forgiving
Fable II
One-button combat, forgiving by design
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dark
Guards run scripted patrol and alert routines
Fable II
Scripted opposition
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dark
Patrols are fixed once observed
Fable II
Fixed world with minor loot rolls
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dark
Skill builds and patrol routing solve each stealth arena
Fable II
Property empire and job economy trivially exploitable
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.