head to head
Neither is simply harder - they are hard in different places. H1Z1 demands more variance; StarCraft demands more optimization.

Execution · Grand Arena
Early battle royale where scavenged loot and shrinking gas decide 150-player brawls.

Optimization · Grand Arena
A real-time strategy classic where perfected build orders and mechanical speed decide most matches.
H1Z1 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.
H1Z1
Gunfights and vehicle control decide duels
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.
H1Z1
Outguessing human rotations and pushes
StarCraft
scouting and predicting human opponent builds
H1Z1 leans clearly harder on variance.
H1Z1
Loot spawns and gas circles randomise runs
StarCraft
minimal hidden info beyond fog of war
StarCraft leans clearly harder on optimization.
H1Z1
Drop spots, loot routes, and zone play
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.