head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is optimization, and it is a single point.

Optimization · Systems & Chaos
A visual novel thriller mixing escape-room puzzles with branching life-or-death story routes.

Optimization · Pure Optimization
A notoriously difficult comedy adventure where Rincewind the inept wizard must rid Ankh-Morpork of a dragon.
999: Nine Hours, Nine Persons, Nine Doors leans Optimization (Systems & Chaos); Discworld 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.
999: Nine Hours, Nine Persons, Nine Doors
Tapping through text and puzzles, zero dexterity
Discworld
Point-and-click; no manual ceiling.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
999: Nine Hours, Nine Persons, Nine Doors
Characters follow a fixed script, never adapt
Discworld
Ankh-Morpork's citizens are scripted gag dispensers.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
999: Nine Hours, Nine Persons, Nine Doors
Hidden story branches and twists drive first playthroughs
Discworld
Infamously obscure puzzle logic blindsides every first-timer.
Discworld leans a little harder on optimization, though the gap is small.
999: Nine Hours, Nine Persons, Nine Doors
Escape-room puzzles and route flowchart are fully solvable
Discworld
Byzantine item chains are brutal but fully solvable.
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.