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

Execution · Pure Mechanics
A two-minute test of joystick reflexes and simple punch-trading rhythm.

Execution · Pure Mechanics
Precise jump execution across fixed levels with secrets to memorise.
Boxing 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.
Boxing
Joystick speed and punch timing decide the two-minute bout
Super Mario World
Perfect inputs trivialise every jump, spin and cape flight
Boxing leans clearly harder on reads.
Boxing
A human second player can be baited and predicted
Super Mario World
Scripted Koopas adapt to nothing
Super Mario World leans a little harder on variance, though the gap is small.
Boxing
Nothing hidden or random in the ring
Super Mario World
Levels are fixed; nothing hidden survives one playthrough
Super Mario World leans clearly harder on optimization.
Boxing
Scoring rules are shallow; positioning tricks are quickly learned
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.