head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Pure Optimization
Iterating cause-and-effect sequences to untangle a fixed narrative puzzle.

Optimization · Pure Optimization
Experimenting with doll abilities to uncover multiple solutions to fixed puzzles.
Last Day of June leans Optimization (Pure Optimization); Stacking leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Last Day of June
Slow walking and simple interactions, no dexterity
Stacking
Hopping between dolls requires no dexterity
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Last Day of June
No opponent - a fixed narrative system
Stacking
Puzzle NPCs are static props, not minds
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Last Day of June
Consequences of changes are hidden until tried
Stacking
Doll abilities are hidden until tried once
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Last Day of June
Sequencing the four characters' actions is the puzzle
Stacking
Finding every solution per puzzle is the real challenge
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.