head to head
Neither is simply harder - they are hard in different places. Micro Machines World Series demands more reads; Super Mario World demands more optimization.

Execution · Pure Mechanics
Twitchy miniature racing where handling beats strategy on chaotic tabletop tracks.

Execution · Pure Mechanics
Precise jump execution across fixed levels with secrets to memorise.
Micro Machines World Series leans Execution (Pure Mechanics); Super Mario World leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Micro Machines World Series
Tiny-car handling on cramped tabletop tracks is twitch-heavy
Super Mario World
Perfect inputs trivialise every jump, spin and cape flight
Micro Machines World Series leans clearly harder on reads.
Micro Machines World Series
Human racers can be baited with weapons and blocks
Super Mario World
Scripted Koopas adapt to nothing
Micro Machines World Series leans clearly harder on variance.
Micro Machines World Series
Pickup spawns and battle chaos add randomness
Super Mario World
Levels are fixed; nothing hidden survives one playthrough
Super Mario World leans clearly harder on optimization.
Micro Machines World Series
Track knowledge is shallow and learned quickly
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.