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

Reads · Grand Arena
A fast card game where the snap mechanic makes reads central.

Optimization · Grand Arena
Blizzard's hero-centric RTS where build-order theory meets surgical unit micro against humans.
Marvel Snap leans Reads (Grand Arena); Warcraft III: Reign of Chaos leans Optimization (Grand Arena).
Warcraft III: Reign of Chaos leans clearly harder on execution.
Marvel Snap
No execution component
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.
Marvel Snap
Snap/retreat decisions are pure opponent psychology
Warcraft III: Reign of Chaos
Scouting and out-guessing a human opponent's tech
Marvel Snap leans clearly harder on variance.
Marvel Snap
Hidden locations and draws drive swings
Warcraft III: Reign of Chaos
Creep routes and item drops add randomness
Warcraft III: Reign of Chaos leans clearly harder on optimization.
Marvel Snap
Deck construction and curve still matter
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.