head to head
Portal 2 asks more than Milo and the Magpies, and the gap is optimization.

Optimization · Pure Optimization
A short point-and-click hidden-object game about a cat finding its way home.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Milo and the Magpies leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Milo and the Magpies
Pure point-and-click, no timing 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.
Milo and the Magpies
Solo cat adventure with no adaptive opponent
Portal 2
No opponent; puzzles are static.
Milo and the Magpies leans a little harder on variance, though the gap is small.
Milo and the Magpies
Hidden objects are fixed, fully mappable
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Milo and the Magpies
Finding objects and solving small fixed puzzles
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.