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
Darker open-city sequel mixing platforming, gunplay, and infamous difficulty spikes.

Execution · Practiced Mastery
An anthology of bite-sized Kirby adventures with deep copy abilities and co-op helpers.
Jak II leans Execution (Practiced Mastery); Kirby Super Star 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.
Jak II
Notoriously demanding missions and gunplay
Kirby Super Star
Helper juggling and The Arena demand competence
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Jak II
Guards and bosses are scripted
Kirby Super Star
Pattern-based bosses throughout
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Jak II
Fixed open city and missions
Kirby Super Star
Treasure locations in Great Cave are fixed
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Jak II
Mission strategies and weapon usage
Kirby Super Star
Ability matchups and boss patterns reward learning
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.