head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Super Thunder Blade demands more execution.

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

Execution · Practiced Mastery
Tests reflex dodging that collapses into memorised safe spots.
Grand Theft Auto V leans Execution (Practiced Mastery); Super Thunder Blade leans Execution (Practiced Mastery).
Super Thunder Blade leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Super Thunder Blade
Weaving the chopper through fire at speed is the whole demand
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Super Thunder Blade
Enemy fire follows fixed 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.
Super Thunder Blade
Stages never change between runs
Super Thunder Blade leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
Super Thunder Blade
Safe-spot and pattern memorisation trivialises repeat runs
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.