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

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

Execution · Light / Casual
Cozy slice-of-life game about delivering mail in a 1980s lakeside town.
Firewatch leans Optimization (Light / Casual); Lake leans Execution (Light / Casual).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Firewatch
Walking and radio dialogue only.
Lake
Just driving a mail truck calmly
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.
Lake
No opposition exists
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.
Lake
Story beats authored, nothing hidden that matters
Firewatch leans a little harder on optimization, though the gap is small.
Firewatch
Few systems to optimize.
Lake
Dialogue choices, no systems to solve
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.