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
Dark-fantasy Doom-engine shooter trading shotguns for elven wands and tomes.

Execution · Practiced Mastery
Darker open-city sequel mixing platforming, gunplay, and infamous difficulty spikes.
Heretic leans Execution (Practiced Mastery); Jak II 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.
Heretic
Classic FPS strafing and aim
Jak II
Notoriously demanding missions and gunplay
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Heretic
Monsters follow fixed 90s AI
Jak II
Guards and bosses are scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Heretic
Static level layouts
Jak II
Fixed open city and missions
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Heretic
Secret hunting, item hoarding, and route knowledge
Jak II
Mission strategies and weapon usage
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.