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.

Optimization · Light / Casual
Cyberpunk horror where a detective hacks the memories of the dying.
Firewatch leans Optimization (Light / Casual); Observer leans Optimization (Light / Casual).
Observer leans a little harder on execution, though the gap is small.
Firewatch
Walking and radio dialogue only.
Observer
Walking with brief stealth segments
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.
Observer
The stalker sequence is scripted
Observer leans a little harder on variance, though the gap is small.
Firewatch
Minor environmental discoveries.
Observer
Unknown story branches and apartment secrets
Observer leans a little harder on optimization, though the gap is small.
Firewatch
Few systems to optimize.
Observer
Investigation logic and clue piecing
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.