head to head
Neither is simply harder - they are hard in different places. Dyson Sphere Program demands more optimization; Fallout: New Vegas demands more execution.

Optimization · Pure Optimization
Solving an interstellar logistics and power-engineering puzzle to construct a Dyson Sphere.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Dyson Sphere Program leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Dyson Sphere Program
All input is construction clicks with no combat ceiling
Fallout: New Vegas
Shooter inputs with VATS assist
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Dyson Sphere Program
No adversary exists in the default game mode
Fallout: New Vegas
Scripted factions and enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dyson Sphere Program
Star system layouts vary per seed but are fully mappable
Fallout: New Vegas
Some loot and crit RNG
Dyson Sphere Program leans clearly harder on optimization.
Dyson Sphere Program
Interstellar logistics and sphere construction are a pure engineering optimisation problem
Fallout: New Vegas
Faction routing, perks, builds heavily 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.