head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is optimization, and it is a single point.

Optimization · Practiced Mastery
An easygoing co-op Kirby about recruiting enemies as friends and combining their elemental powers.

Optimization · Pure Optimization
Crossover LEGO brawler where the right hero power unlocks every secret.
Kirby Star Allies leans Optimization (Practiced Mastery); LEGO Marvel Super Heroes leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby Star Allies
Very low difficulty, AI allies carry fights
LEGO Marvel Super Heroes
Mashy hero combat, no fail pressure
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby Star Allies
Friend AI helps rather than opposes
LEGO Marvel Super Heroes
Scripted villains
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby Star Allies
Fixed layouts and bosses
LEGO Marvel Super Heroes
Collectibles fixed in place
LEGO Marvel Super Heroes leans a little harder on optimization, though the gap is small.
Kirby Star Allies
Friend-ability element combos solve puzzles
LEGO Marvel Super Heroes
Hero-power gating across a collectible open New York
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.