head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Practiced Mastery
A storybook underwater metroidvania about a girl piloting a homemade submarine to find her father.

Optimization · Practiced Mastery
Open-world Hyrule built on physics puzzles and exploration over reflex tests.
Song of the Deep leans Optimization (Practiced Mastery); The Legend of Zelda: Breath of the Wild leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Song of the Deep
Gentle submarine handling and claw manipulation
The Legend of Zelda: Breath of the Wild
Parry timing and aiming matter but forgiving.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Song of the Deep
Scripted sea creatures
The Legend of Zelda: Breath of the Wild
Enemies follow fixed scripted behaviors.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Song of the Deep
Unknown undersea map first dive
The Legend of Zelda: Breath of the Wild
Weapon drops and weather lightly randomized.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Song of the Deep
Environmental puzzles and upgrade routing carry the game
The Legend of Zelda: Breath of the Wild
Shrines, cooking, traversal routes fully 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.