head to head
Neither is simply harder - they are hard in different places. StarCraft demands more optimization; Warhammer 40,000: Dawn of War II demands more variance.

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

Execution · Grand Arena
Hero-driven squad RTS where wargear optimization and ability timing combine with reading aggressive opponents.
StarCraft leans Optimization (Grand Arena); Warhammer 40,000: Dawn of War II leans Execution (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
StarCraft
APM and micro control ceiling is huge
Warhammer 40,000: Dawn of War II
Hero ability activation and squad retreat timing are mechanically demanding
Warhammer 40,000: Dawn of War II leans a little harder on reads, though the gap is small.
StarCraft
scouting and predicting human opponent builds
Warhammer 40,000: Dawn of War II
Opponent army composition and hero focus must be predicted
Warhammer 40,000: Dawn of War II leans clearly harder on variance.
StarCraft
minimal hidden info beyond fog of war
Warhammer 40,000: Dawn of War II
Retreat damage, wargear drops, and map control variance add uncertainty
StarCraft leans clearly harder on optimization.
StarCraft
build orders and economy are near-solvable
Warhammer 40,000: Dawn of War II
Wargear builds and ability upgrade sequences are optimizable
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.