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
The archetypal idle game where optimal purchase order is the entire skill.

Optimization · Pure Optimization
Optimizing regional economics and city services to sustain growth without collapsing your budget.
Cookie Clicker leans Optimization (Pure Optimization); SimCity 4 leans Optimization (Pure Optimization).
SimCity 4 leans a little harder on execution, though the gap is small.
Cookie Clicker
Clicking is optional past the early game
SimCity 4
Point-and-click placement; zero reflex requirement
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Cookie Clicker
No opponent
SimCity 4
Solo sandbox with no adversarial pressure
SimCity 4 leans a little harder on variance, though the gap is small.
Cookie Clicker
Golden cookie timing randomness
SimCity 4
Neighbor city interactions and demand curves add unpredictability
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Cookie Clicker
Purchase order and ascension math are the game
SimCity 4
Budget, ordinances, and transport networks are the core puzzle
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.