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

Optimization · Pure Optimization
Cargo-hauling odyssey where route planning and loadout matter most.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Death Stranding leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Death Stranding
Balance and traversal inputs, modest demands.
Portal 2
Portal placement requires some precision but timing is lenient.
Death Stranding leans a little harder on reads, though the gap is small.
Death Stranding
BTs and MULEs scripted, predictable.
Portal 2
No opponent; puzzles are static.
Death Stranding leans clearly harder on variance.
Death Stranding
Terrain, weather, BT spawns randomized.
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Death Stranding
Cargo loadouts, routes, structures highly 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.