head to head
Neither is simply harder - they are hard in different places. ARC Raiders demands more variance; StarCraft demands more optimization.

Execution · Grand Arena
An extraction shooter where scavengers dodge killer machines and rival squads for loot.

Optimization · Grand Arena
A real-time strategy classic where perfected build orders and mechanical speed decide most matches.
ARC Raiders leans Execution (Grand Arena); StarCraft leans Optimization (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
ARC Raiders
Gunplay and movement under machine fire
StarCraft
APM and micro control ceiling is huge
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
ARC Raiders
Rival squads ambush, bait, and adapt
StarCraft
scouting and predicting human opponent builds
ARC Raiders leans clearly harder on variance.
ARC Raiders
Loot spawns and unknown player positions
StarCraft
minimal hidden info beyond fog of war
StarCraft leans clearly harder on optimization.
ARC Raiders
Loadout economy and map knowledge compound
StarCraft
build orders and economy are near-solvable
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.