head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

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

Execution · Practiced Mastery
Sprawling action horror with four campaigns and a surprisingly deep combat system.
Grand Theft Auto V leans Execution (Practiced Mastery); Resident Evil 6 leans Execution (Practiced Mastery).
Resident Evil 6 leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Resident Evil 6
Deep melee-and-gunplay movement system rewards mechanics
Grand Theft Auto V leans a little harder on reads, though the gap is small.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Resident Evil 6
Agent Hunt PvP adds a sliver of prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Some mission and lobby randomness.
Resident Evil 6
Set-piece campaigns are fixed after first sight
Resident Evil 6 leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
Resident Evil 6
Skill builds and Mercenaries combos are 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.