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 stealth sim about casing houses and planning optimal heists.
Fallout: New Vegas leans Optimization (Pure Optimization); Thief Simulator 2 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
Thief Simulator 2
Lockpicking and stealth timing matter but stay light
Thief Simulator 2 leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
Thief Simulator 2
NPC patrols follow scripted routes, not adaptive
Thief Simulator 2 leans a little harder on variance, though the gap is small.
Fallout: New Vegas
Some loot and crit RNG
Thief Simulator 2
Loot contents and patrol timing add mild uncertainty
Fallout: New Vegas leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Thief Simulator 2
Planning routes, tools and casing targets is the core
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.