head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Rory McIlroy PGA Tour demands more optimization.

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

Execution · Practiced Mastery
EA's Frostbite-powered golf game mixing swing timing with course-management decisions.
Grand Theft Auto V leans Execution (Practiced Mastery); Rory McIlroy PGA Tour leans Execution (Practiced Mastery).
Rory McIlroy PGA Tour leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Rory McIlroy PGA Tour
Swing timing and putt pace are the physical test
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Rory McIlroy PGA Tour
No adaptive opponent; the course never reacts
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.
Rory McIlroy PGA Tour
Wind and lie randomness nudge shots
Rory McIlroy PGA Tour leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Rory McIlroy PGA Tour
Club selection and course management decide scores
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.