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
A sandbox city builder that is pure traffic and zoning optimization.

Optimization · Pure Optimization
A first-person factory builder that is pure logistics optimization.
Cities: Skylines leans Optimization (Pure Optimization); Satisfactory leans Optimization (Pure Optimization).
Satisfactory leans a little harder on execution, though the gap is small.
Cities: Skylines
No reflex demands at all.
Satisfactory
Light platforming, no real mechanical ceiling.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Cities: Skylines
No adaptive opponent exists in the sandbox.
Satisfactory
No adaptive opponent in the world.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Cities: Skylines
Minor disaster events if enabled.
Satisfactory
Resource nodes are fixed once mapped.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Cities: Skylines
Traffic flow, zoning, and budgets are fully solvable.
Satisfactory
Ratios, logistics, and factory layout are everything.
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.