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
An aggressive soulslike about punishing fixed boss patterns with tight dodging.

Execution · Practiced Mastery
The original Souls game: scripted boss patterns you solve with builds, routes and disciplined execution.
Bloodborne leans Execution (Practiced Mastery); Demon's Souls leans Execution (Practiced Mastery).
Bloodborne leans a little harder on execution, though the gap is small.
Bloodborne
Aggressive dodges and rally timing demand sharp hands.
Demon's Souls
Stamina-timed dodges and parries punish sloppy hands.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Bloodborne
Bosses follow fixed movesets; no model of you.
Demon's Souls
Invasions exist but bosses are scripted patterns.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Bloodborne
Chalice dungeon layouts and drops add some randomness.
Demon's Souls
World tendency and upgrade drops add mild noise.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Bloodborne
Builds, weapons, and boss patterns are studyable and solvable.
Demon's Souls
Builds, routes and learned movesets are 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.