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 · Competitive PvP
A shallow novelty wrestler testing little beyond basic timing and weapon grabs.

Execution · Pure Mechanics
Motion-controlled tennis, bowling, golf, baseball and boxing built around simple swing gestures.
Celebrity Deathmatch leans Execution (Competitive PvP); Wii Sports leans Execution (Pure Mechanics).
Wii Sports leans a little harder on execution, though the gap is small.
Celebrity Deathmatch
Button timing wins matches but the ceiling is low
Wii Sports
Motion swing timing and accuracy decide every event
Celebrity Deathmatch leans a little harder on reads, though the gap is small.
Celebrity Deathmatch
A couch opponent can be conditioned, shallowly
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.
Celebrity Deathmatch
Random weapon drops shake up the ring
Wii Sports
Minor physics wobble and CPU behaviour randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Celebrity Deathmatch
Learning each celebrity's finisher exhausts the depth fast
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.