head to head
Neither is simply harder - they are hard in different places. Nintendo World Cup demands more reads; Super Mario Odyssey demands more execution.

Execution · Pure Mechanics
Arcade soccer testing reflex tackles and super-shot timing.

Execution · Pure Mechanics
A 3D platformer whose joy lives in tight movement and capture-driven traversal.
Nintendo World Cup leans Execution (Pure Mechanics); Super Mario Odyssey leans Execution (Pure Mechanics).
Super Mario Odyssey leans clearly harder on execution.
Nintendo World Cup
Tackles and super-shot timing decide most goals
Super Mario Odyssey
Precise platforming and capture-move tech ceiling.
Nintendo World Cup leans clearly harder on reads.
Nintendo World Cup
Versus a human, shot fakes add light prediction
Super Mario Odyssey
No adaptive opponents whatsoever.
Nintendo World Cup leans a little harder on variance, though the gap is small.
Nintendo World Cup
Ball physics add minor chaos
Super Mario Odyssey
Almost no randomness in level design.
Super Mario Odyssey leans clearly harder on optimization.
Nintendo World Cup
Learning super-move triggers is a small solvable layer
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.