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

Execution · Practiced Mastery
A toy-soldier shooter testing basic aim through fixed plastic battlefields.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Army Men: Sarge's Heroes leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Army Men: Sarge's Heroes
Clunky third-person aiming carries the campaign
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans a little harder on reads, though the gap is small.
Army Men: Sarge's Heroes
Split-screen versus adds a sliver of human prediction
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Army Men: Sarge's Heroes
Levels are fixed with little hidden
Grand Theft Auto V
Some mission and lobby randomness.
Grand Theft Auto V leans a little harder on optimization, though the gap is small.
Army Men: Sarge's Heroes
Weapon pickups and routes barely need planning
Grand Theft Auto V
Heists, money loops, builds learnable.
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.