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
Island-themed collection of twelve motion-controlled sports showcasing the Wii MotionPlus accessory.
Mario & Sonic at the Olympic Games leans Execution (Pure Mechanics); Wii Sports Resort 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 Resort
MotionPlus precision in swordplay, archery and bowling
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 Resort
Local versus duels involve mild feinting
Wii Sports Resort 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 Resort
Slight physics and CPU pattern 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 Resort
Each event has small learnable technique optima
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.