head to head
Fallout: New Vegas asks more than Observation, and the gap is optimization.

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

Optimization · Pure Optimization
Sci-fi thriller played as the station AI solving its own crisis.
Fallout: New Vegas leans Optimization (Pure Optimization); Observation leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
Observation
Camera control and interface manipulation
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
Observation
Events are fully authored
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
Observation
Mystery unknown until uncovered
Fallout: New Vegas leans clearly harder on optimization.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Observation
Systems puzzles and station schematics solving
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.