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 · Pure Optimization
A zombie survival sim where long-term planning outweighs moment-to-moment skill.

Optimization · Systems & Chaos
Managing a survivor community's economy and risk under permadeath randomness.
Project Zomboid leans Optimization (Pure Optimization); State of Decay 2 leans Optimization (Systems & Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Combat is deliberate; precision matters but is slow.
State of Decay 2
Combat is forgiving; stealth and swings need modest timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Zombies follow scripted behaviour; no adaptation.
State of Decay 2
Zombies and hostile NPCs follow randomised scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Loot spawns and zombie distributions randomized.
State of Decay 2
Permadeath, infestations and survivor traits randomise each community
Project Zomboid leans a little harder on optimization, though the gap is small.
Project Zomboid
Skill grinding, base setup, and routing define survival.
State of Decay 2
Base building, resource routing and survivor management drive survival
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.