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

Execution · Pure Mechanics
The 70s-cinema getaway driving game with famously demanding physics.

Execution · Pure Mechanics
A 3D marble-rolling platformer through skyborne courses.
Driver leans Execution (Pure Mechanics); Marble Skies 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.
Driver
Handbrake control and pursuit driving by feel
Marble Skies
precise marble control through 3D courses
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Driver
Police AI is mappable
Marble Skies
no opponent, solo time-trial platforming
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Driver
Traffic adds mild unpredictability
Marble Skies
fixed level layouts, minimal randomness
Driver leans a little harder on optimization, though the gap is small.
Driver
City routes and mission tactics learnable
Marble Skies
route memorization for best times
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.