head to head
Dead or Alive Xtreme Beach Volleyball asks more than Garry's Mod, and the gap is execution.

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

Reads · Light / Casual
Source-engine sandbox whose community modes range from building to social deduction.
Dead or Alive Xtreme Beach Volleyball leans Execution (Practiced Mastery); Garry's Mod leans Reads (Light / Casual).
Dead or Alive Xtreme Beach Volleyball leans clearly harder on execution.
Dead or Alive Xtreme Beach Volleyball
Volleyball rallies need timing but stay deliberately forgiving
Garry's Mod
Varies by mode; base sandbox is undemanding
Garry's Mod leans a little harder on reads, though the gap is small.
Dead or Alive Xtreme Beach Volleyball
Versus humans adds light shot prediction
Garry's Mod
Social deduction modes like TTT involve humans
Garry's Mod leans a little harder on variance, though the gap is small.
Dead or Alive Xtreme Beach Volleyball
Partner mood and gift systems behave semi-randomly
Garry's Mod
Hidden roles and player chaos in popular modes
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
Garry's Mod
Contraption building rewards systems knowledge
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.