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.

Variance · Light / Casual
A relaxing hidden-object game finding 100 cats in alien scenes.

Optimization · Light / Casual
A gorgeous first-person mystery about piecing together a boy's disappearance.
100 Aliens Cats leans Variance (Light / Casual); The Vanishing of Ethan Carter 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.
100 Aliens Cats
Pointing and clicking needs no dexterity
The Vanishing of Ethan Carter
Walking and looking, nothing more
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
100 Aliens Cats
Solo hidden-object game with no opponent
The Vanishing of Ethan Carter
No opponent
100 Aliens Cats leans a little harder on variance, though the gap is small.
100 Aliens Cats
Cat positions are hidden until found
The Vanishing of Ethan Carter
The mystery is hidden only until discovered
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
100 Aliens Cats
Methodical searching speeds completion
The Vanishing of Ethan Carter
Reconstructing event sequences is light deduction
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.