head to head
Neither is simply harder - they are hard in different places. Bravely Default demands more variance; Portal 2 demands more execution.

Optimization · Pure Optimization
A classic-styled JRPG whose brave/default system turns turns themselves into a resource.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Bravely Default leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Bravely Default
Turn-based menus; no physical demands
Portal 2
Portal placement requires some precision but timing is lenient.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Bravely Default
Bosses follow fixed scripts
Portal 2
No opponent; puzzles are static.
Bravely Default leans clearly harder on variance.
Bravely Default
Minor drop and encounter randomness
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans a little harder on optimization, though the gap is small.
Bravely Default
Job combos and brave/default economy are deeply solvable
Portal 2
Solving the puzzle's logic IS the entire game.
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.