head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
The fastest mainline Souls, distilling the formula into aggressive boss duels.

Execution · Practiced Mastery
Simulation driving precision paired with a deep, solvable tuning and setup layer.
Dark Souls III leans Execution (Practiced Mastery); Gran Turismo 5 leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Dark Souls III
fast roll timing against aggressive scripted bosses
Gran Turismo 5
Simulation-grade car control and braking precision lead everything
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dark Souls III
PvP invasions exist but are optional
Gran Turismo 5
AI fields are predictable; online racing stays positional
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dark Souls III
fixed encounters converge after first sight
Gran Turismo 5
Tracks and physics are deterministic
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dark Souls III
movesets and builds are fully mappable
Gran Turismo 5
Tuning setups, gear ratios and license-test lines are deeply solvable
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.