head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Cornering execution over memorisable circuits, with light prediction in wheel-to-wheel multiplayer.

Execution · Practiced Mastery
Toy-car arcade racer about drift-charging boost on loop-the-loop tracks.
Grid 2 leans Execution (Practiced Mastery); Hot Wheels Unleashed 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.
Grid 2
Car control through corners is the entire moment-to-moment test
Hot Wheels Unleashed
Drift-boost management on twisting plastic tracks
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grid 2
Online wheel-to-wheel adds light positional prediction
Hot Wheels Unleashed
Online races add light human jockeying
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grid 2
Tracks are fixed and fully visible
Hot Wheels Unleashed
Car unboxing randomness outside races
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Grid 2
Racing lines, braking points and car selection are studyable
Hot Wheels Unleashed
Car tiers, upgrades, and racing lines
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.