head to head
Neither is simply harder - they are hard in different places. Gwent: The Witcher Card Game demands more reads; Hearthstone demands more variance.

Reads · Mind & Math
A bluffing-heavy card game where reading your opponent across three rounds outweighs raw card power.

Variance · Grand Arena
A digital card game balancing opponent reads against draw variance.
Gwent: The Witcher Card Game leans Reads (Mind & Math); Hearthstone leans Variance (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Gwent: The Witcher Card Game
No timing involved; purely strategic card placement
Hearthstone
Clicks only, no mechanical skill
Gwent: The Witcher Card Game leans clearly harder on reads.
Gwent: The Witcher Card Game
Two-out-of-three rounds create meta-game bluffing and baiting
Hearthstone
Human opponents bluff and adapt mid-match
Hearthstone leans clearly harder on variance.
Gwent: The Witcher Card Game
Card draws and hidden hand matter but deck is known
Hearthstone
Draw RNG and discover effects swing games
Gwent: The Witcher Card Game leans a little harder on optimization, though the gap is small.
Gwent: The Witcher Card Game
Row control and point denial strategies are analytically solvable
Hearthstone
Deckbuilding, mulligans, and mana curves matter
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.