Building comparison
head to head
DayZvsZ1 Battle Royale
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.
DayZ
Variance · Grand Arena
Hardcore survival sandbox where other players are scarier than the zombies.
Z1 Battle Royale
Execution · Grand Arena
An early battle royale shooter where dozens of players loot, drive, and shoot to be the last one standing.
DayZ leans Variance (Grand Arena); Z1 Battle Royale leans Execution (Grand Arena).
DayZZ1 Battle Royale
Axis by axis
Execution6 vs 7
Z1 Battle Royale leans a little harder on execution, though the gap is small.
DayZ
gunfights punish slow hands severely
Z1 Battle Royale
Gunplay, bullet drop, and car control under pressure
Reads6 vs 6
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
DayZ
every survivor met may lie, ambush, or befriend
Z1 Battle Royale
Human opponents rotate, bait, and adapt to you
Variance7 vs 6
DayZ leans a little harder on variance, though the gap is small.
DayZ
loot spawns and who you meet are unknowable
Z1 Battle Royale
Loot spawns, drop locations, and gas circles
Optimization5 vs 4
DayZ leans a little harder on optimization, though the gap is small.
DayZ
map knowledge and survival routines compound
Z1 Battle Royale
Loadout and rotation strategy is a thinner layer
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.