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 faction-driven RPG-shooter where build and route planning shape every ending.

Optimization · Pure Optimization
A musou spinoff of Fire Emblem: Three Houses blending hack-and-slash combat with light tactics.
Fallout: New Vegas leans Optimization (Pure Optimization); Fire Emblem Warriors: Three Hopes 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.
Fallout: New Vegas
Shooter inputs with VATS assist
Fire Emblem Warriors: Three Hopes
Real-time combat is forgiving hack-and-slash
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
Fire Emblem Warriors: Three Hopes
Enemy commanders follow scripted AI
Fallout: New Vegas leans a little harder on variance, though the gap is small.
Fallout: New Vegas
Some loot and crit RNG
Fire Emblem Warriors: Three Hopes
Minor drop and recruitment randomness
Fallout: New Vegas leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Fire Emblem Warriors: Three Hopes
Class builds, unit orders, weapon triangle, map management decide battles
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.