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
Managing provinces, taxes and legions as a solvable empire-building system.

Optimization · Pure Optimization
Lane defense classic about managing a sun economy against shambling waves.
Centurion: Defender of Rome leans Optimization (Pure Optimization); Plants vs. Zombies 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.
Centurion: Defender of Rome
Issuing orders and chariot minigames need little dexterity
Plants vs. Zombies
Clicking to plant, minimal pressure
Centurion: Defender of Rome leans a little harder on reads, though the gap is small.
Centurion: Defender of Rome
AI rivals follow fixed diplomatic and military logic
Plants vs. Zombies
Zombie waves follow set compositions
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Centurion: Defender of Rome
Battle outcomes and rival behaviour carry some hidden randomness
Plants vs. Zombies
Wave timing and lane pressure vary mildly
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Centurion: Defender of Rome
Provincial economy, taxation and legion deployment are solvable systems
Plants vs. Zombies
Sun economy and lane setups are near-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.