head to head
Neither is simply harder - they are hard in different places. Chip 'n Dale Rescue Rangers demands more execution; Grand Theft Auto V demands more reads.

Execution · Practiced Mastery
Crisp NES licensed platformer about chipmunks hurling crates at robots.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Chip 'n Dale Rescue Rangers leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Chip 'n Dale Rescue Rangers leans clearly harder on execution.
Chip 'n Dale Rescue Rangers
Tight jumps and box-throw timing
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Chip 'n Dale Rescue Rangers
Enemies are simple fixed patterns
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.
Chip 'n Dale Rescue Rangers
Deterministic levels
Grand Theft Auto V
Some mission and lobby randomness.
Chip 'n Dale Rescue Rangers leans a little harder on optimization, though the gap is small.
Chip 'n Dale Rescue Rangers
Level memory and boss pattern knowledge
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.