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

Execution · Pure Mechanics
A crossover Olympic sports collection where waggle timing and mashing form set the podium.

Execution · Pure Mechanics
Motion-controlled tennis, bowling, golf, baseball and boxing built around simple swing gestures.
Mario & Sonic at the Olympic Games leans Execution (Pure Mechanics); Wii Sports leans Execution (Pure Mechanics).
Mario & Sonic at the Olympic Games leans a little harder on execution, though the gap is small.
Mario & Sonic at the Olympic Games
Motion timing and mashing rhythm decide event results
Wii Sports
Motion swing timing and accuracy decide every event
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mario & Sonic at the Olympic Games
Human rivals race in parallel; little interaction
Wii Sports
Casual local opponents add light mind games
Wii Sports leans a little harder on variance, though the gap is small.
Mario & Sonic at the Olympic Games
Events are fixed; almost no randomness
Wii Sports
Minor physics wobble and CPU behaviour randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mario & Sonic at the Olympic Games
Learning each event's optimal technique caps quickly
Wii Sports
Simple technique tricks like bowling spin are learnable
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.