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

Execution · Twitch Chaos
An endless runner about sprinting down a hospital corridor full of zombies.

Execution · Practiced Mastery
The original top-down crime sandbox where you rack up points causing mayhem across three cities.
Corridor Z leans Execution (Twitch Chaos); 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.
Corridor Z
reaction timing to avoid zombie hazards
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.
Corridor Z
no opponent, scripted zombie AI
Grand Theft Auto
Cops follow simple scripts; nothing adapts
Corridor Z leans a little harder on variance, though the gap is small.
Corridor Z
random hazard and item placement
Grand Theft Auto
Chaotic traffic and wanted-level escalation surprise players
Grand Theft Auto leans a little harder on optimization, though the gap is small.
Corridor Z
minor upgrade and route strategy
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.