head to head
Neither is simply harder - they are hard in different places. Portal 2 demands more execution; World of Final Fantasy demands more variance.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.

Optimization · Pure Optimization
A chibi Final Fantasy spin-off about capturing monsters and stacking them into totem teams.
Portal 2 leans Optimization (Pure Optimization); World of Final Fantasy leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Portal 2
Portal placement requires some precision but timing is lenient.
World of Final Fantasy
Turn-based stacking combat; no dexterity
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Portal 2
No opponent; puzzles are static.
World of Final Fantasy
Scripted bosses with fixed gimmicks
World of Final Fantasy leans clearly harder on variance.
Portal 2
Puzzles are deterministic with no randomness.
World of Final Fantasy
Mirage capture conditions hidden until learned
Portal 2 leans clearly harder on optimization.
Portal 2
Solving the puzzle's logic IS the entire game.
World of Final Fantasy
Stack composition and mirage boards are a solvable system
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.