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
Linear JRPG built around real-time paradigm switching and stagger combat.

Optimization · Pure Optimization
An open-ended needs-and-money system that rewards efficient scheduling.
Final Fantasy XIII leans Optimization (Pure Optimization); The Sims leans Optimization (Pure Optimization).
Final Fantasy XIII leans a little harder on execution, though the gap is small.
Final Fantasy XIII
Paradigm shifts need timely menu reactions
The Sims
Clicking menus has no physical ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy XIII
Scripted stagger-phase bosses
The Sims
Sims run need-driven scripts, not minds
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy XIII
Minor randomness in enemy actions
The Sims
Event rolls add flavour, all quickly mapped
Final Fantasy XIII leans a little harder on optimization, though the gap is small.
Final Fantasy XIII
Paradigm sequencing and stagger timing are solvable
The Sims
Need scheduling, career grinding and money loops 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.