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

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

Optimization · Pure Optimization
A first-person shop management sim about stocking shelves, setting prices and growing a small supermarket.
Final Fantasy XIII leans Optimization (Pure Optimization); Supermarket Simulator 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.
Final Fantasy XIII
Paradigm shifts need timely menu reactions
Supermarket Simulator
Stocking and checkout are light manual busywork.
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
Supermarket Simulator
Customers follow simple scripted demand.
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
Supermarket Simulator
Daily customer flow varies a little.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy XIII
Paradigm sequencing and stagger timing are solvable
Supermarket Simulator
Pricing margins, ordering and shelf layout drive growth.
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.