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
An underwater survival game won by methodical tech progression.

Optimization · Pure Optimization
An open-world JRPG where build construction and art rotation planning win battles.
Subnautica leans Optimization (Pure Optimization); Xenoblade Chronicles 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.
Subnautica
Movement is slow; no precision demands.
Xenoblade Chronicles
Positioning during auto-attack combat needs minimal dexterity
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Subnautica
Creatures follow scripted patrols; no adaptation.
Xenoblade Chronicles
Enemy AI runs fixed aggro and art rotations
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Subnautica
Resource node placement mildly randomized.
Xenoblade Chronicles
Drop rates and unexplored zones add mild uncertainty
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Subnautica
Tech progression and base routing solve the ocean.
Xenoblade Chronicles
Art rotations, gem crafting and party builds decide fights
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.