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

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

Execution · Practiced Mastery
An open-world racing MMO about collecting cars and cruising Ibiza and Hawaii.
Grand Theft Auto V leans Execution (Practiced Mastery); Test Drive Unlimited 2 leans Execution (Practiced Mastery).
Test Drive Unlimited 2 leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Test Drive Unlimited 2
Open-road car control decides races
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.
Test Drive Unlimited 2
Online rivals add mild jockeying
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Some mission and lobby randomness.
Test Drive Unlimited 2
Traffic and weather add small noise
Test Drive Unlimited 2 leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
Test Drive Unlimited 2
Car choice, upgrades, and route knowledge compound
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.