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
Beautiful 19th-century city-builder ruled by production ratios.

Optimization · Pure Optimization
A sandbox city builder that is pure traffic and zoning optimization.
Anno 1800 leans Optimization (Pure Optimization); Cities: Skylines leans Optimization (Pure Optimization).
Anno 1800 leans a little harder on execution, though the gap is small.
Anno 1800
pausable, no twitch
Cities: Skylines
No reflex demands at all.
Anno 1800 leans a little harder on reads, though the gap is small.
Anno 1800
AI scripted, not adaptive
Cities: Skylines
No adaptive opponent exists in the sandbox.
Anno 1800 leans a little harder on variance, though the gap is small.
Anno 1800
minor trade fluctuations
Cities: Skylines
Minor disaster events if enabled.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Anno 1800
supply chains and ratios are the game
Cities: Skylines
Traffic flow, zoning, and budgets are fully 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.