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
A puzzle-forward adventure testing creative lateral thinking against a fixed authored solution space.

Optimization · Pure Optimization
A mechanical journey adventure solved by understanding the logic of its automaton-filled world.
Return to Monkey Island leans Optimization (Pure Optimization); Syberia 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.
Return to Monkey Island
Modern hint system and relaxed interface remove all reflex demands
Syberia
Walking and clicking; zero reflex demand
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Return to Monkey Island
Entirely authored puzzles with no adaptive opponent
Syberia
NPCs follow scripted dialogue trees with no adaptive modelling
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Return to Monkey Island
Virtually no randomness; solutions are static
Syberia
Linear journey with virtually no hidden-information surprises
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Return to Monkey Island
Lateral-thinking item puzzles require mapping cause and effect chains
Syberia
Mechanical clockwork puzzles require mapping part relationships
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.