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
A 2D sandbox of procedurally generated planets driven by crafting progression.

Optimization · Pure Optimization
A blade-driven JRPG won by chain-attack routing and combo optimization.
Starbound leans Optimization (Pure Optimization); Xenoblade Chronicles 2 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.
Starbound
Light platforming and combat, generous margins
Xenoblade Chronicles 2
Auto-attack with art-timing inputs
Xenoblade Chronicles 2 leans a little harder on reads, though the gap is small.
Starbound
Procedural NPCs follow simple fixed behaviours
Xenoblade Chronicles 2
Scripted enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Starbound
Procedural planets and loot keep early exploration unknown
Xenoblade Chronicles 2
Blade gacha and crit rolls
Xenoblade Chronicles 2 leans a little harder on optimization, though the gap is small.
Starbound
Gear tiers, farming, and progression routes dominate
Xenoblade Chronicles 2
Blade combos and chain attack routing central
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.