head to head
Helldivers 2 asks more than Grand Theft Auto V, and the gap is variance.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Optimization · Practiced Mastery
Top-tier co-op shooter against bug and bot hordes.
Grand Theft Auto V leans Execution (Practiced Mastery); Helldivers 2 leans Optimization (Practiced Mastery).
Helldivers 2 leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Helldivers 2
Recoil, stratagem inputs, friendly-fire aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Helldivers 2
Enemies scripted, no adaptive opponent
Helldivers 2 leans clearly harder on variance.
Grand Theft Auto V
Some mission and lobby randomness.
Helldivers 2
Patrol spawns and modifiers shake missions
Helldivers 2 leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Helldivers 2
Loadout and stratagem synergies deep
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.