head to head
Neither is simply harder - they are hard in different places. Montaro : RE demands more variance; Super Mario World demands more optimization.

Execution · Pure Mechanics
A comedic reflex platformer testing jump timing against fast obstacles.

Execution · Pure Mechanics
Precise jump execution across fixed levels with secrets to memorise.
Montaro : RE leans Execution (Pure Mechanics); Super Mario World leans Execution (Pure Mechanics).
Montaro : RE leans a little harder on execution, though the gap is small.
Montaro : RE
Reflex jumping and timing carry this runner-platformer
Super Mario World
Perfect inputs trivialise every jump, spin and cape flight
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Montaro : RE
No adaptive opponent in a solo arcade game
Super Mario World
Scripted Koopas adapt to nothing
Montaro : RE leans clearly harder on variance.
Montaro : RE
Some procedural obstacles add randomness
Super Mario World
Levels are fixed; nothing hidden survives one playthrough
Super Mario World leans clearly harder on optimization.
Montaro : RE
Little to solve beyond reacting to obstacles
Super Mario World
Secret exits and route knowledge add a modest solvable layer
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.