head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Optimization · Pure Optimization
Lane defense classic about managing a sun economy against shambling waves.

Optimization · Pure Optimization
Tests long-horizon planning of city economics and mappable political systems.
Plants vs. Zombies leans Optimization (Pure Optimization); Urban Empire 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.
Plants vs. Zombies
Clicking to plant, minimal pressure
Urban Empire
Menu-driven city management, no twitch component
Urban Empire leans a little harder on reads, though the gap is small.
Plants vs. Zombies
Zombie waves follow set compositions
Urban Empire
Council AI votes by mappable rules, not adaptive scheming
Urban Empire leans a little harder on variance, though the gap is small.
Plants vs. Zombies
Wave timing and lane pressure vary mildly
Urban Empire
Historical events and council moods are hidden until learned
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Plants vs. Zombies
Sun economy and lane setups are near-solvable
Urban Empire
Budget, district planning and political math are solvable systems
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.