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

Optimization · Pure Optimization
A classic Greek city builder of housing blocks, gods, and mythic monsters.
Cookie Clicker leans Optimization (Pure Optimization); Zeus: Master of Olympus 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.
Cookie Clicker
Clicking is optional past the early game
Zeus: Master of Olympus
Paused-friendly mouse planning
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
Zeus: Master of Olympus
Rival cities act on schedules
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Cookie Clicker
Golden cookie timing randomness
Zeus: Master of Olympus
Monster attacks and god visits semi-random
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
Zeus: Master of Olympus
Walker logic, housing blocks, and economy are deeply 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.