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
Solving an interstellar logistics and power-engineering puzzle to construct a Dyson Sphere.
Cities: Skylines leans Optimization (Pure Optimization); Dyson Sphere Program leans Optimization (Pure Optimization).
Dyson Sphere Program leans a little harder on execution, though the gap is small.
Cities: Skylines
No reflex demands at all.
Dyson Sphere Program
All input is construction clicks with no combat 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.
Dyson Sphere Program
No adversary exists in the default game mode
Dyson Sphere Program leans a little harder on variance, though the gap is small.
Cities: Skylines
Minor disaster events if enabled.
Dyson Sphere Program
Star system layouts vary per seed but are fully mappable
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.
Dyson Sphere Program
Interstellar logistics and sphere construction are a pure engineering optimisation problem
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.