head to head
Wii Sports asks more than Dead or Alive Xtreme Beach Volleyball, and the gap is execution.

Execution · Practiced Mastery
Light volleyball timing wrapped in a gift-economy vacation sim.

Execution · Pure Mechanics
Motion-controlled tennis, bowling, golf, baseball and boxing built around simple swing gestures.
Dead or Alive Xtreme Beach Volleyball leans Execution (Practiced Mastery); Wii Sports leans Execution (Pure Mechanics).
Wii Sports leans clearly harder on execution.
Dead or Alive Xtreme Beach Volleyball
Volleyball rallies need timing but stay deliberately forgiving
Wii Sports
Motion swing timing and accuracy decide every event
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dead or Alive Xtreme Beach Volleyball
Versus humans adds light shot prediction
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.
Dead or Alive Xtreme Beach Volleyball
Partner mood and gift systems behave semi-randomly
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.
Dead or Alive Xtreme Beach Volleyball
Managing partner relationships and money is the deeper loop
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.