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 · Practiced Mastery
A basic arcade soccer game testing input timing and simple positioning.

Execution · Pure Mechanics
Motion-controlled tennis, bowling, golf, baseball and boxing built around simple swing gestures.
Champions World Class Soccer leans Execution (Practiced Mastery); Wii Sports 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.
Champions World Class Soccer
Passing, shooting and tackling timing carry every play
Wii Sports
Motion swing timing and accuracy decide every event
Champions World Class Soccer leans a little harder on reads, though the gap is small.
Champions World Class Soccer
Two-player mode lets you predict a human opponent
Wii Sports
Casual local opponents add light mind games
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Champions World Class Soccer
Little randomness once team ratings are known
Wii Sports
Minor physics wobble and CPU behaviour randomness
Champions World Class Soccer leans a little harder on optimization, though the gap is small.
Champions World Class Soccer
Formation choice and team selection give a known edge
Wii Sports
Simple technique tricks like bowling spin are 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.