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

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

Execution · Pure Mechanics
Island-themed collection of twelve motion-controlled sports showcasing the Wii MotionPlus accessory.
Nintendo World Cup leans Execution (Pure Mechanics); Wii Sports Resort leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Nintendo World Cup
Tackles and super-shot timing decide most goals
Wii Sports Resort
MotionPlus precision in swordplay, archery and bowling
Nintendo World Cup leans a little harder on reads, though the gap is small.
Nintendo World Cup
Versus a human, shot fakes add light prediction
Wii Sports Resort
Local versus duels involve mild feinting
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Nintendo World Cup
Ball physics add minor chaos
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.
Nintendo World Cup
Learning super-move triggers is a small solvable layer
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.