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

Optimization · Pure Optimization
Optimising bureaucratic scheduling, bribery and sabotage inside an authored dystopia.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Beholder 2 leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Beholder 2
Clicking through tasks and minigames needs no dexterity
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.
Beholder 2
Coworkers and citizens follow authored scripts
Portal 2
No opponent; puzzles are static.
Beholder 2 leans clearly harder on variance.
Beholder 2
Document details and event outcomes hide information
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Beholder 2
Scheduling work, bribes and career sabotage is solvable strategy
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.