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

Optimization · Pure Optimization
A farm-life sim solved by season routing and profit optimization.
Plants vs. Zombies leans Optimization (Pure Optimization); Stardew Valley 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
Stardew Valley
Trivial timing on fishing and combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Plants vs. Zombies
Zombie waves follow set compositions
Stardew Valley
No adaptive opponent exists
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Plants vs. Zombies
Wave timing and lane pressure vary mildly
Stardew Valley
Crop luck and geode RNG matter modestly
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
Stardew Valley
Routing seasons, profit loops, and bundles dominates
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.