head to head
Neither is simply harder - they are hard in different places. StarCraft demands more optimization; Street Fighter IV demands more execution.

Optimization · Grand Arena
A real-time strategy classic where perfected build orders and mechanical speed decide most matches.

Execution · Grand Arena
A high-execution fighter where one-frame links and opponent modelling separate competitors.
StarCraft leans Optimization (Grand Arena); Street Fighter IV leans Execution (Grand Arena).
Street Fighter IV leans clearly harder on execution.
StarCraft
APM and micro control ceiling is huge
Street Fighter IV
One-frame links and FADC combos demand extreme motor precision
Street Fighter IV leans clearly harder on reads.
StarCraft
scouting and predicting human opponent builds
Street Fighter IV
Reading opponent habits, wake-up patterns, and adaptations is the meta
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
StarCraft
minimal hidden info beyond fog of war
Street Fighter IV
Virtually no RNG; every outcome is skill-driven
StarCraft leans clearly harder on optimization.
StarCraft
build orders and economy are near-solvable
Street Fighter IV
Frame data, punish windows, and matchup charts are deeply studied
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.