head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Mike Tyson's Punch-Out!! demands more execution.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Execution · Practiced Mastery
NES boxing game built entirely on memorizing opponent tells and executing split-second counters.
Grand Theft Auto V leans Execution (Practiced Mastery); Mike Tyson's Punch-Out!! leans Execution (Practiced Mastery).
Mike Tyson's Punch-Out!! leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Mike Tyson's Punch-Out!!
Frame-tight dodges and counters, brutal at Tyson
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Mike Tyson's Punch-Out!!
Every boxer follows fixed tells and patterns
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Mike Tyson's Punch-Out!!
Almost fully deterministic once patterns are known
Mike Tyson's Punch-Out!! leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Mike Tyson's Punch-Out!!
Memorizing each opponent's pattern is half the game
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.