head to head
Neither is simply harder - they are hard in different places. Dark and Darker demands more variance; Warcraft III: Reign of Chaos demands more optimization.

Reads · Grand Arena
Tests slow-melee dueling and predicting human extraction squads under loot RNG.

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.
Dark and Darker leans Reads (Grand Arena); Warcraft III: Reign of Chaos leans Optimization (Grand Arena).
Warcraft III: Reign of Chaos leans a little harder on execution, though the gap is small.
Dark and Darker
Slow melee timing, spacing and spell aim decide fights
Warcraft III: Reign of Chaos
Micro of heroes and units decides fights
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dark and Darker
Third-partying, baiting and outplaying human squads is central
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
Dark and Darker leans clearly harder on variance.
Dark and Darker
Loot rolls, spawns and circle placement shape every raid
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Warcraft III: Reign of Chaos leans clearly harder on optimization.
Dark and Darker
Gear economy, class builds and dungeon routes reward grinding knowledge
Warcraft III: Reign of Chaos
Build orders, creeping routes, and matchup theory run deep
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.