head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Pure Mechanics
Arcade racing lines and traffic-dodging reflexes on memorisable tracks.

Execution · Pure Mechanics
Holding clean lines at speed through traffic on memorisable point-to-point roads.
Test Drive 6 leans Execution (Pure Mechanics); The Need for Speed 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.
Test Drive 6
Cornering at speed through traffic is the entire challenge
The Need for Speed
Holding racing lines at speed through traffic is the test
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Test Drive 6
AI racers follow rubber-band scripts, not minds to model
The Need for Speed
AI rivals and police follow fixed behaviour
The Need for Speed leans a little harder on variance, though the gap is small.
Test Drive 6
Traffic adds mild unpredictability to known tracks
The Need for Speed
Traffic patterns add mild run-to-run noise
Test Drive 6 leans a little harder on optimization, though the gap is small.
Test Drive 6
Learning racing lines and car choice is solvable
The Need for Speed
Track knowledge and car choice settle quickly
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.