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.

Execution · Practiced Mastery
Dash-precision platforming with solvable boss orders and upgrade routing.

Execution · Practiced Mastery
Movement execution and route optimisation through a fixed, mappable planet.
Mega Man X5 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 X5
Dash-jump precision and boss dodge timing demand clean hands
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 X5
Mavericks cycle fixed attack patterns
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.
Mega Man X5
Random ending triggers add rare unmapped outcomes
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 X5
Armor parts, boss order and route knowledge 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.