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 collection of short stories about a family's strange deaths.
Firewatch leans Optimization (Light / Casual); What Remains of Edith Finch leans Execution (Light / Casual).
What Remains of Edith Finch leans a little harder on execution, though the gap is small.
Firewatch
Walking and radio dialogue only.
What Remains of Edith Finch
Varied vignettes require light input skill.
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.
What Remains of Edith Finch
No adversaries.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Firewatch
Minor environmental discoveries.
What Remains of Edith Finch
Stories are fixed.
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.
What Remains of Edith Finch
Little to optimize.
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.