head to head
Neither is simply harder - they are hard in different places. Deadly Premonition 2: A Blessing in Disguise demands more variance; Portal 2 demands more optimization.

Optimization · Pure Optimization
The sequel-prequel sends Agent York skateboarding around a Louisiana town to solve another surreal murder case.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Deadly Premonition 2: A Blessing in Disguise leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans a little harder on execution, though the gap is small.
Deadly Premonition 2: A Blessing in Disguise
Skateboarding and light combat ask little of the hands
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.
Deadly Premonition 2: A Blessing in Disguise
Enemies are scripted nuisances, never adaptive
Portal 2
No opponent; puzzles are static.
Deadly Premonition 2: A Blessing in Disguise leans clearly harder on variance.
Deadly Premonition 2: A Blessing in Disguise
Unknown town events and clues on a first investigation
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Deadly Premonition 2: A Blessing in Disguise
Daily scheduling, crafting, and routing are the real systems
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.