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
A Pixar-styled action adventure about a spirit guide cleansing a corrupted forest.

Execution · Practiced Mastery
Third-person action where Captain Titus chainswords through ork hordes without a cover system.
Kena: Bridge of Spirits leans Execution (Practiced Mastery); Warhammer 40,000: Space Marine leans Execution (Practiced Mastery).
Warhammer 40,000: Space Marine leans a little harder on execution, though the gap is small.
Kena: Bridge of Spirits
Parry and dodge timing in boss fights
Warhammer 40,000: Space Marine
Melee-shooting flow and execution timing carry combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Kena: Bridge of Spirits
Corrupted spirits are fully scripted
Warhammer 40,000: Space Marine
Ork hordes follow scripted aggression
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Kena: Bridge of Spirits
World is fixed and explorable
Warhammer 40,000: Space Marine
Encounters are fixed and predictable
Kena: Bridge of Spirits leans a little harder on optimization, though the gap is small.
Kena: Bridge of Spirits
Rot ability usage and boss pattern learning
Warhammer 40,000: Space Marine
Weapon choice and fury management are simple to learn
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.