head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Velocity Ultra demands more execution.

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

Execution · Practiced Mastery
A speedrun shooter testing teleport execution against optimised level routes.
Grand Theft Auto V leans Execution (Practiced Mastery); Velocity Ultra leans Execution (Practiced Mastery).
Velocity Ultra leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Velocity Ultra
Teleport precision at full throttle defines perfect medals
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Velocity Ultra
Hazards are fixed level geometry, not minds
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Velocity Ultra
Levels are identical every attempt
Velocity Ultra leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Velocity Ultra
Route planning through bomb switches is half the score chase
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.