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

Optimization · Practiced Mastery
A gag-driven platformer testing little beyond collectible patience.
Kirby Star Allies leans Optimization (Practiced Mastery); The Simpsons Game leans Optimization (Practiced Mastery).
The Simpsons Game leans a little harder on execution, though the gap is small.
Kirby Star Allies
Very low difficulty, AI allies carry fights
The Simpsons Game
Simple platforming and character-power timing
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
The Simpsons Game
Parody enemies are jokes on rails
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
The Simpsons Game
Levels are fixed gag sequences
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby Star Allies
Friend-ability element combos solve puzzles
The Simpsons Game
Character-ability puzzles and collectibles are lightly solvable
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.