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.

Execution · Practiced Mastery
A gentle platformer where copying enemy abilities and light timing carries progress.

Optimization · Practiced Mastery
A relaxed collect-athon testing character-ability matching far more than any skill ceiling.
Kirby: Nightmare in Dream Land leans Execution (Practiced Mastery); LEGO Batman 2: DC Super Heroes leans Optimization (Practiced Mastery).
Kirby: Nightmare in Dream Land leans a little harder on execution, though the gap is small.
Kirby: Nightmare in Dream Land
light platforming and timing precision
LEGO Batman 2: DC Super Heroes
Button-mashing combat designed for children's hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby: Nightmare in Dream Land
scripted enemies, no adaptation
LEGO Batman 2: DC Super Heroes
Enemies are harmless scripted waves
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby: Nightmare in Dream Land
minimal randomness
LEGO Batman 2: DC Super Heroes
Stud and minikit locations are fixed once known
LEGO Batman 2: DC Super Heroes leans a little harder on optimization, though the gap is small.
Kirby: Nightmare in Dream Land
ability combos lightly solvable
LEGO Batman 2: DC Super Heroes
Matching character abilities to gated collectibles
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.