head to head
Neither is simply harder - they are hard in different places. BoxBoxBoy! demands more optimization; The Elder Scrolls V: Skyrim demands more variance.

Optimization · Pure Optimization
A minimalist puzzle platformer about deducing box-chain solutions.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
BoxBoxBoy! leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans a little harder on execution, though the gap is small.
BoxBoxBoy!
Box creation and movement need no precision
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
BoxBoxBoy!
Solo puzzle game with no opponent
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
The Elder Scrolls V: Skyrim leans clearly harder on variance.
BoxBoxBoy!
Puzzles fully deterministic, nothing random
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
BoxBoxBoy! leans clearly harder on optimization.
BoxBoxBoy!
Deducing box-chain shapes to clear obstacles is the game
The Elder Scrolls V: Skyrim
Skill stacking, enchant loops, and exploits are deeply solvable.
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.