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

Optimization · Pure Optimization
Painterly turn-based RPG built around interrupting enemies on a shared timeline.

Optimization · Pure Optimization
Linear JRPG built around real-time paradigm switching and stagger combat.
Child of Light 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.
Child of Light
Timeline interrupts need only light timing
Final Fantasy XIII
Paradigm shifts need timely menu reactions
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Child of Light
Enemy AI is scripted
Final Fantasy XIII
Scripted stagger-phase bosses
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Child of Light
Minor drop randomness
Final Fantasy XIII
Minor randomness in enemy actions
Child of Light leans a little harder on optimization, though the gap is small.
Child of Light
Timeline manipulation, oculi crafting, skill trees
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.