head to head
Neither is simply harder - they are hard in different places. Donkey Kong Country 2: Diddy's Kong Quest demands more execution; Grand Theft Auto V demands more reads.

Execution · Practiced Mastery
The fan-favourite sequel with harder levels and deeper secrets.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Donkey Kong Country 2: Diddy's Kong Quest leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Donkey Kong Country 2: Diddy's Kong Quest leans clearly harder on execution.
Donkey Kong Country 2: Diddy's Kong Quest
Demanding jump chains and animal-buddy control
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Donkey Kong Country 2: Diddy's Kong Quest
Fixed enemy patterns, no adaptation
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.
Donkey Kong Country 2: Diddy's Kong Quest
Secret Lost World entrances hidden until found
Grand Theft Auto V
Some mission and lobby randomness.
Donkey Kong Country 2: Diddy's Kong Quest leans a little harder on optimization, though the gap is small.
Donkey Kong Country 2: Diddy's Kong Quest
Routes, DK coins, and bonuses fully mappable
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.