head to head
Neither is simply harder - they are hard in different places. StarCraft demands more optimization; Tekken Tag Tournament demands more reads.

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

Execution · Grand Arena
A tag-team 3D fighter layering team optimization onto Tekken's execution and reads core.
StarCraft leans Optimization (Grand Arena); Tekken Tag Tournament leans Execution (Grand Arena).
Tekken Tag Tournament leans a little harder on execution, though the gap is small.
StarCraft
APM and micro control ceiling is huge
Tekken Tag Tournament
Tag combos and netsu juggles demand precise inputs
Tekken Tag Tournament leans clearly harder on reads.
StarCraft
scouting and predicting human opponent builds
Tekken Tag Tournament
Tag timing adds another layer of human mind-games
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
Open information; nothing hidden between rounds
StarCraft leans clearly harder on optimization.
StarCraft
build orders and economy are near-solvable
Tekken Tag Tournament
Team synergy and tag combo routing are optimizable systems
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.