head to head
Neither is simply harder - they are hard in different places. Double Dragon II: The Revenge demands more execution; Grand Theft Auto V demands more reads.

Execution · Practiced Mastery
A classic beat 'em up sequel where the Lee brothers avenge Marian with kicks and knees.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Double Dragon II: The Revenge leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Double Dragon II: The Revenge leans clearly harder on execution.
Double Dragon II: The Revenge
Directional attacks and knee timing carry every fight
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Double Dragon II: The Revenge
Enemy thugs use fixed AI routines
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.
Double Dragon II: The Revenge
Minor enemy positioning randomness
Grand Theft Auto V
Some mission and lobby randomness.
Double Dragon II: The Revenge leans a little harder on optimization, though the gap is small.
Double Dragon II: The Revenge
Learning stage layouts and abusing the hyper knee
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.