head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Light / Casual
A first-person mystery about a fire lookout in a Wyoming forest.

Execution · Light / Casual
A puzzle horror game about learning trap solutions through trial and error.
Firewatch leans Optimization (Light / Casual); The Witch's House MV leans Execution (Light / Casual).
The Witch's House MV leans a little harder on execution, though the gap is small.
Firewatch
Walking and radio dialogue only.
The Witch's House MV
occasional quick reactions to avoid death traps
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Firewatch
No adaptive opposition.
The Witch's House MV
no adaptive opponent, puzzle-driven horror
The Witch's House MV leans a little harder on variance, though the gap is small.
Firewatch
Minor environmental discoveries.
The Witch's House MV
some trial-and-error trap randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Firewatch
Few systems to optimize.
The Witch's House MV
learning correct puzzle solutions
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.