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

Optimization · Pure Optimization
Free-to-play action MMORPG where gear progression eclipses moment-to-moment skill.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Neverwinter leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Neverwinter leans a little harder on execution, though the gap is small.
Neverwinter
Action-combat dodges and rotations, fairly lenient
Portal 2
Portal placement requires some precision but timing is lenient.
Neverwinter leans clearly harder on reads.
Neverwinter
Light PvP modes exist
Portal 2
No opponent; puzzles are static.
Neverwinter leans clearly harder on variance.
Neverwinter
Loot drops and enchant rolls
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Neverwinter
Gear-score grind and build optimization dominate
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.