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.

Execution · Practiced Mastery
An arcade FPS that scores you for killing enemies in the most creative ways possible.

Execution · Practiced Mastery
Simulation driving precision underpinned by setup tuning and race strategy.
Bulletstorm leans Execution (Practiced Mastery); Project CARS leans Execution (Practiced Mastery).
Project CARS leans a little harder on execution, though the gap is small.
Bulletstorm
Leash, kick, and shot timing drive skillshot chains
Project CARS
Braking points and wheel control at the sim limit
Project CARS leans a little harder on reads, though the gap is small.
Bulletstorm
Enemies are scripted fodder for your combos
Project CARS
Online racecraft against humans adds light positional prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Bulletstorm
Arenas and spawns are fixed and learnable
Project CARS
Dynamic weather injects some session randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Bulletstorm
Maximising skillshot score per arena is a solvable puzzle
Project CARS
Setup tuning and pit strategy reward deep study
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.