head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
A free co-op top-down shooter about a marine squad purging alien-infested colonies.

Execution · Practiced Mastery
The original top-down crime sandbox where you rack up points causing mayhem across three cities.
Alien Swarm leans Execution (Practiced Mastery); Grand Theft Auto 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.
Alien Swarm
Top-down aim and friendly-fire discipline
Grand Theft Auto
Twitchy top-down driving and shooting under police pressure
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Alien Swarm
Swarm AI scripted by director triggers
Grand Theft Auto
Cops follow simple scripts; nothing adapts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Alien Swarm
Spawn timing varies modestly
Grand Theft Auto
Chaotic traffic and wanted-level escalation surprise players
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Alien Swarm
Class loadouts and route knowledge decide runs
Grand Theft Auto
Score targets reward learning missions and city layouts
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.