head to head
Warcraft III: Reign of Chaos asks more than Command & Conquer: Red Alert 3, and the gap is optimization.

Reads · Grand Arena
Three-faction Cold-War RTS with naval combat where faction asymmetry and multi-front pressure are the core tests.

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.
Command & Conquer: Red Alert 3 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.
Command & Conquer: Red Alert 3
Naval and air micro alongside base-building taxes player bandwidth
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.
Command & Conquer: Red Alert 3
Three-faction asymmetry means opponent choices must be constantly predicted
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert 3
Ore spawning and naval choke variance add moderate uncertainty
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Warcraft III: Reign of Chaos leans clearly harder on optimization.
Command & Conquer: Red Alert 3
Production order and defensive placement are learnable but more flexible
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.