head to head
Neither is simply harder - they are hard in different places. StarCraft demands more optimization; Tekken Tag Tournament 2 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 tag-enhanced Tekken that multiplies execution demands and opponent reads by adding partner management to every exchange.
StarCraft leans Optimization (Grand Arena); Tekken Tag Tournament 2 leans Execution (Grand Arena).
Tekken Tag Tournament 2 leans clearly harder on execution.
StarCraft
APM and micro control ceiling is huge
Tekken Tag Tournament 2
Tag combos and partner launcher extensions demand high motor precision
Tekken Tag Tournament 2 leans clearly harder on reads.
StarCraft
scouting and predicting human opponent builds
Tekken Tag Tournament 2
Tag crash timing and incoming character reads against humans are constant
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
Tekken Tag Tournament 2
No RNG; all information is visible
StarCraft leans clearly harder on optimization.
StarCraft
build orders and economy are near-solvable
Tekken Tag Tournament 2
Tag team pairings and shared health management reward deep preparation
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.