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

Execution · Practiced Mastery
The original Souls game: scripted boss patterns you solve with builds, routes and disciplined execution.

Optimization · Practiced Mastery
Build optimization and learned monster weak points, executed through physical climb-and-strike combat.
Demon's Souls leans Execution (Practiced Mastery); Dragon's Dogma: Dark Arisen leans Optimization (Practiced Mastery).
Demon's Souls leans a little harder on execution, though the gap is small.
Demon's Souls
Stamina-timed dodges and parries punish sloppy hands.
Dragon's Dogma: Dark Arisen
Climbing monsters and timing skills demands real combat dexterity
Demon's Souls leans a little harder on reads, though the gap is small.
Demon's Souls
Invasions exist but bosses are scripted patterns.
Dragon's Dogma: Dark Arisen
Pawns and monsters follow learnable scripted behaviours
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Demon's Souls
World tendency and upgrade drops add mild noise.
Dragon's Dogma: Dark Arisen
Bitterblack loot rolls and night spawns add managed randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Demon's Souls
Builds, routes and learned movesets are fully solvable.
Dragon's Dogma: Dark Arisen
Vocation builds, augment stacking and monster weak-point knowledge dominate
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.