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.

Execution · Practiced Mastery
Simulation driving precision underpinned by setup tuning and race strategy.

Execution · Practiced Mastery
Consistent precision driving on top of a solvable car-setup and racing-line layer.
Project CARS leans Execution (Practiced Mastery); World Circuit: The Grand Prix Race Simulation leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Project CARS
Braking points and wheel control at the sim limit
World Circuit: The Grand Prix Race Simulation
Lap-after-lap precision driving decides every race outcome
Project CARS leans a little harder on reads, though the gap is small.
Project CARS
Online racecraft against humans adds light positional prediction
World Circuit: The Grand Prix Race Simulation
AI drivers follow fixed racing lines, not minds
Project CARS leans a little harder on variance, though the gap is small.
Project CARS
Dynamic weather injects some session randomness
World Circuit: The Grand Prix Race Simulation
Weather adds minor unpredictability to otherwise deterministic racing
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Project CARS
Setup tuning and pit strategy reward deep study
World Circuit: The Grand Prix Race Simulation
Car setup, gear ratios and racing lines are solvable engineering
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.