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
An easygoing co-op Kirby about recruiting enemies as friends and combining their elemental powers.
Kirby's Return to Dream Land leans Optimization (Practiced Mastery); Kirby Star Allies leans Optimization (Practiced Mastery).
Kirby's Return to Dream Land 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
Kirby Star Allies
Very low difficulty, AI allies carry fights
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
Kirby Star Allies
Friend AI helps rather than opposes
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
Kirby Star Allies
Fixed layouts and bosses
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Kirby's Return to Dream Land
Super ability timing and sphere collection are solvable
Kirby Star Allies
Friend-ability element combos solve 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.