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
Aggressive circuit racing testing car control over memorisable tracks and braking points.

Execution · Pure Mechanics
Arcade racing lines and traffic-dodging reflexes on memorisable tracks.
Race Driver: Grid leans Execution (Practiced Mastery); Test Drive 6 leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Race Driver: Grid
Aggressive wheel-to-wheel car control is the core demand
Test Drive 6
Cornering at speed through traffic is the entire challenge
Race Driver: Grid leans a little harder on reads, though the gap is small.
Race Driver: Grid
Online racing adds light opponent positioning awareness
Test Drive 6
AI racers follow rubber-band scripts, not minds to model
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Race Driver: Grid
Damage outcomes add slight unpredictability to contact
Test Drive 6
Traffic adds mild unpredictability to known tracks
Race Driver: Grid leans a little harder on optimization, though the gap is small.
Race Driver: Grid
Braking points, lines and flashback management are learnable
Test Drive 6
Learning racing lines and car choice is solvable
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.