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.

Execution · Practiced Mastery
A monochrome puzzle-platformer about a boy lost in limbo.

Optimization · Practiced Mastery
A gentle physics puzzle-platformer starring a creature made of unraveling yarn.
Limbo leans Execution (Practiced Mastery); Unravel leans Optimization (Practiced Mastery).
Limbo leans a little harder on execution, though the gap is small.
Limbo
Tight platforming with trial-and-error.
Unravel
Gentle platforming and yarn-swing timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Limbo
Hazards are scripted.
Unravel
No opponent
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Limbo
No randomness.
Unravel
Everything is visible and fixed
Unravel leans a little harder on optimization, though the gap is small.
Limbo
Puzzles have fixed solutions.
Unravel
Physics puzzles with discoverable intended solutions
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.