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
Gleefully gory physics platformer about surviving user-made obstacle courses.

Execution · Pure Mechanics
A 3D platformer whose joy lives in tight movement and capture-driven traversal.
Happy Wheels leans Execution (Pure Mechanics); Super Mario Odyssey leans Execution (Pure Mechanics).
Super Mario Odyssey leans a little harder on execution, though the gap is small.
Happy Wheels
Twitchy ragdoll vehicle control through traps
Super Mario Odyssey
Precise platforming and capture-move tech ceiling.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Happy Wheels
Levels are static obstacle courses
Super Mario Odyssey
No adaptive opponents whatsoever.
Happy Wheels leans a little harder on variance, though the gap is small.
Happy Wheels
Physics wobble adds run-to-run chaos
Super Mario Odyssey
Almost no randomness in level design.
Super Mario Odyssey leans a little harder on optimization, though the gap is small.
Happy Wheels
Trap memorisation and route choice
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.