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 pastel platformer where Yoshi carries Baby Mario and perfect scores demand finding everything.

Execution · Practiced Mastery
Movement execution and route optimisation through a fixed, mappable planet.
Super Mario World 2: Yoshi's Island leans Execution (Practiced Mastery); Super Metroid leans Execution (Practiced Mastery).
Super Metroid leans a little harder on execution, though the gap is small.
Super Mario World 2: Yoshi's Island
Egg-aiming and flutter jumps for 100 percent scores
Super Metroid
Wall-jumps, shinesparks and boss dodges demand precise inputs
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Super Mario World 2: Yoshi's Island
All enemies are scripted
Super Metroid
Bosses cycle fixed patterns, never adapting
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Super Mario World 2: Yoshi's Island
Collectibles hidden only until found
Super Metroid
Item and route knowledge is fixed once discovered
Super Metroid leans a little harder on optimization, though the gap is small.
Super Mario World 2: Yoshi's Island
Perfect-score runs demand full collectible routing
Super Metroid
Sequence-breaking route optimisation is the enduring meta-game
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.