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

Optimization · Light / Casual
A relaxed hidden-object hunt for cats with no pressure of any kind.

Optimization · Light / Casual
A first-person mystery about a fire lookout in a Wyoming forest.
An Arcade Full of Cats leans Optimization (Light / Casual); Firewatch leans Optimization (Light / Casual).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
An Arcade Full of Cats
Clicking cats requires only patience
Firewatch
Walking and radio dialogue only.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
An Arcade Full of Cats
Nothing opposes you
Firewatch
No adaptive opposition.
An Arcade Full of Cats leans a little harder on variance, though the gap is small.
An Arcade Full of Cats
Hidden cats are unknown until found, then done
Firewatch
Minor environmental discoveries.
An Arcade Full of Cats leans a little harder on optimization, though the gap is small.
An Arcade Full of Cats
Systematic scene-scanning is the only technique
Firewatch
Few systems 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.