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.

Optimization · Practiced Mastery
A four-player Wii Kirby romp gathering ship parts for the stranded alien Magolor.

Optimization · Practiced Mastery
A lovingly pixelled aerial adventure where Otus carries gunner friends through floating islands.
Kirby's Return to Dream Land leans Optimization (Practiced Mastery); Owlboy leans Optimization (Practiced Mastery).
Owlboy leans a little harder on execution, though the gap is small.
Kirby's Return to Dream Land
Easygoing main game; EX mode adds modest demands
Owlboy
Flying and gunner-swapping in light combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby's Return to Dream Land
Bosses are pattern-scripted
Owlboy
Scripted pirates and bosses
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby's Return to Dream Land
Energy sphere hiding spots are static secrets
Owlboy
Hand-crafted, deterministic world
Owlboy leans a little harder on optimization, though the gap is small.
Kirby's Return to Dream Land
Super ability timing and sphere collection are solvable
Owlboy
Boss patterns and secrets 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.