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

Execution · Practiced Mastery
Pattern memorisation and precise platforming with a solvable boss-order route.

Execution · Practiced Mastery
Movement execution and route optimisation through a fixed, mappable planet.
Mega Man 5 leans Execution (Practiced Mastery); Super Metroid leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man 5
Precise jumps and buster timing through gauntlet stages
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.
Mega Man 5
Robot Masters cycle fixed attack patterns
Super Metroid
Bosses cycle fixed patterns, never adapting
Super Metroid leans a little harder on variance, though the gap is small.
Mega Man 5
Every stage and boss is identical each attempt
Super Metroid
Item and route knowledge is fixed once discovered
Super Metroid leans a little harder on optimization, though the gap is small.
Mega Man 5
Weapon-order routing and pattern memorisation solve the game
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.