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

Reads · Grand Arena
A turn-based wizard duel mixing bluff, spell-cast odds, and tactical board control.

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.
Chaos Reborn leans Reads (Grand Arena); Warcraft III: Reign of Chaos leans Optimization (Grand Arena).
Warcraft III: Reign of Chaos leans clearly harder on execution.
Chaos Reborn
Clicking units involves no twitch dimension
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.
Chaos Reborn
Bluffing illusion spells against human wizards is central
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
Chaos Reborn leans clearly harder on variance.
Chaos Reborn
Spell-cast success and draws are dice-driven
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Warcraft III: Reign of Chaos leans a little harder on optimization, though the gap is small.
Chaos Reborn
Board control and creature trading reward solid theory
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.