head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.

Optimization · Pure Optimization
A class-swapping JRPG carried by art-rotation and ouroboros build optimization.
Fallout: New Vegas leans Optimization (Pure Optimization); Xenoblade Chronicles 3 leans Optimization (Pure Optimization).
Fallout: New Vegas leans a little harder on execution, though the gap is small.
Fallout: New Vegas
Shooter inputs with VATS assist
Xenoblade Chronicles 3
Auto-attack with art-timing inputs
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Scripted factions and enemies
Xenoblade Chronicles 3
Scripted enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Some loot and crit RNG
Xenoblade Chronicles 3
Loot and gem rolls
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Xenoblade Chronicles 3
Class, art, and ouroboros builds deeply rewarded
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.