head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Moving Out demands more optimization.

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

Optimization · Practiced Mastery
A slapstick co-op moving simulator about hurling furniture into a truck against the clock.
Grand Theft Auto V leans Execution (Practiced Mastery); Moving Out leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Moving Out
Physics carrying, throwing, and steering under time pressure
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Moving Out
No adaptive opposition; pure co-op chaos
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.
Moving Out
Ragdoll physics adds slapstick unpredictability
Moving Out leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Moving Out
Routing furniture and splitting tasks drives gold times
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.