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
Island-themed collection of twelve motion-controlled sports showcasing the Wii MotionPlus accessory.

Execution · Competitive PvP
Arcade wrestling that tests reversal timing and little else by design.
Wii Sports Resort leans Execution (Pure Mechanics); WWE 2K Battlegrounds leans Execution (Competitive PvP).
Wii Sports Resort leans a little harder on execution, though the gap is small.
Wii Sports Resort
MotionPlus precision in swordplay, archery and bowling
WWE 2K Battlegrounds
Button-mash combos and reversal timing set the pace
WWE 2K Battlegrounds leans a little harder on reads, though the gap is small.
Wii Sports Resort
Local versus duels involve mild feinting
WWE 2K Battlegrounds
Human opponents add light reversal mind games
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Wii Sports Resort
Slight physics and CPU pattern randomness
WWE 2K Battlegrounds
Power-ups and interactive arenas inject party chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Wii Sports Resort
Each event has small learnable technique optima
WWE 2K Battlegrounds
Shallow systems - move knowledge helps a little
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.