head to head
Hot Wheels Unleashed asks more than Grand Theft Auto V, and the gap is execution.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Execution · Practiced Mastery
Toy-car arcade racer about drift-charging boost on loop-the-loop tracks.
Grand Theft Auto V leans Execution (Practiced Mastery); Hot Wheels Unleashed leans Execution (Practiced Mastery).
Hot Wheels Unleashed leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
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.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Hot Wheels Unleashed
Online races add light human jockeying
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Hot Wheels Unleashed
Car unboxing randomness outside races
Hot Wheels Unleashed leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
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.