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
Precision car control of vintage machinery refined through setup and line study.

Execution · Practiced Mastery
Simulation driving precision underpinned by setup tuning and race strategy.
GT Legends leans Execution (Practiced Mastery); Project CARS 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.
GT Legends
Historic cars without aids demand precise car control every corner
Project CARS
Braking points and wheel control at the sim limit
Project CARS leans a little harder on reads, though the gap is small.
GT Legends
Racecraft versus humans exists but pace dominates
Project CARS
Online racecraft against humans adds light positional prediction
Project CARS leans a little harder on variance, though the gap is small.
GT Legends
Conditions are known before the green flag
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.
GT Legends
Setup tuning and line study are where lap time lives
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.