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
A narrative horror game tested primarily by puzzle knowledge and sanity-resource management.

Optimization · Pure Optimization
Linear JRPG built around real-time paradigm switching and stagger combat.
Amnesia: Rebirth leans Optimization (Pure Optimization); Final Fantasy XIII leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Amnesia: Rebirth
Stealth and evasion; no real twitch demands
Final Fantasy XIII
Paradigm shifts need timely menu reactions
Amnesia: Rebirth leans a little harder on reads, though the gap is small.
Amnesia: Rebirth
Enemies patrol fixed routes; no adaptive opponent
Final Fantasy XIII
Scripted stagger-phase bosses
Amnesia: Rebirth leans a little harder on variance, though the gap is small.
Amnesia: Rebirth
Some encounter timing has variance; story rooms are fixed
Final Fantasy XIII
Minor randomness in enemy actions
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Amnesia: Rebirth
Resource management, narrative puzzles and safe-path knowledge are solvable
Final Fantasy XIII
Paradigm sequencing and stagger timing 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.