head to head
Neither is simply harder - they are hard in different places. PlayerUnknown's Battlegrounds demands more variance; Warcraft III: Reign of Chaos demands more optimization.

Execution · Grand Arena
The battle royale archetype: loot, rotate, and outlast 99 opponents inside a shrinking circle.

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.
PlayerUnknown's Battlegrounds leans Execution (Grand Arena); Warcraft III: Reign of Chaos leans Optimization (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
PlayerUnknown's Battlegrounds
Recoil control and long-range ballistics
Warcraft III: Reign of Chaos
Micro of heroes and units decides fights
Warcraft III: Reign of Chaos leans a little harder on reads, though the gap is small.
PlayerUnknown's Battlegrounds
99 humans rotating and ambushing adaptively
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
PlayerUnknown's Battlegrounds leans clearly harder on variance.
PlayerUnknown's Battlegrounds
Loot spawns and circle placement shape every match
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Warcraft III: Reign of Chaos leans clearly harder on optimization.
PlayerUnknown's Battlegrounds
Zone rotations and positioning theory are learnable
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.