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

Optimization · Practiced Mastery
Gentle minigame variety - flying, potions, duels - with no demanding axis.

Optimization · Practiced Mastery
A 3DS Kirby playing with foreground-background depth and the vacuum-everything Hypernova power.
Harry Potter and the Half-Blood Prince leans Optimization (Practiced Mastery); Kirby: Triple Deluxe leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Harry Potter and the Half-Blood Prince
Quidditch ring-chasing and duel timing are gentle
Kirby: Triple Deluxe
Easy main game, modest arena challenges
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Harry Potter and the Half-Blood Prince
Duelling NPCs follow simple fixed patterns
Kirby: Triple Deluxe
Bosses follow fixed patterns
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Harry Potter and the Half-Blood Prince
Hogwarts tasks are scripted and repeatable
Kirby: Triple Deluxe
Levels fully deterministic
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Harry Potter and the Half-Blood Prince
Potion-stirring sequences and castle routing are lightly solvable
Kirby: Triple Deluxe
Sun-stone hunting and foreground-background gimmick puzzles
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.