head to head
Neither is simply harder - they are hard in different places. Mario & Sonic at the Olympic Winter Games demands more reads; Super Mario Odyssey demands more execution.

Execution · Pure Mechanics
Party-sized motion-timing contests with learnable per-event techniques.

Execution · Pure Mechanics
A 3D platformer whose joy lives in tight movement and capture-driven traversal.
Mario & Sonic at the Olympic Winter Games leans Execution (Pure Mechanics); Super Mario Odyssey leans Execution (Pure Mechanics).
Super Mario Odyssey leans clearly harder on execution.
Mario & Sonic at the Olympic Winter Games
Motion-timing and button precision decide every event
Super Mario Odyssey
Precise platforming and capture-move tech ceiling.
Mario & Sonic at the Olympic Winter Games leans clearly harder on reads.
Mario & Sonic at the Olympic Winter Games
Local human rivals add mild prediction in head-to-head events
Super Mario Odyssey
No adaptive opponents whatsoever.
Mario & Sonic at the Olympic Winter Games leans a little harder on variance, though the gap is small.
Mario & Sonic at the Olympic Winter Games
Events are fixed; minor physics wobble
Super Mario Odyssey
Almost no randomness in level design.
Super Mario Odyssey leans clearly harder on optimization.
Mario & Sonic at the Olympic Winter Games
Each event has a learnable optimal technique
Super Mario Odyssey
Moon routes and movement tech 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.