head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Metal Gear Rising: Revengeance demands more execution.

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

Execution · Practiced Mastery
High-speed cyborg slasher built on precise parries and slicing anything in half.
Grand Theft Auto V leans Execution (Practiced Mastery); Metal Gear Rising: Revengeance leans Execution (Practiced Mastery).
Metal Gear Rising: Revengeance leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Metal Gear Rising: Revengeance
parry timing and blade-mode cuts demand sharp reactions
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Metal Gear Rising: Revengeance
bosses telegraph 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.
Metal Gear Rising: Revengeance
deterministic encounters
Metal Gear Rising: Revengeance leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Metal Gear Rising: Revengeance
learning movesets and upgrade priorities
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.