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
Pre-solving battles through ship design and deployment, then watching the answer play out.

Optimization · Pure Optimization
Lane defense classic about managing a sun economy against shambling waves.
Gratuitous Space Battles 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.
Gratuitous Space Battles
Battles run hands-off once deployed
Plants vs. Zombies
Clicking to plant, minimal pressure
Gratuitous Space Battles leans a little harder on reads, though the gap is small.
Gratuitous Space Battles
Async challenges exist but fleets cannot adapt mid-fight
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.
Gratuitous Space Battles
Unknown enemy loadouts add pre-battle hidden information
Plants vs. Zombies
Wave timing and lane pressure vary mildly
Gratuitous Space Battles leans a little harder on optimization, though the gap is small.
Gratuitous Space Battles
Ship design and deployment orders decide everything before combat starts
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.