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.

Variance · Grand Arena
Hardcore survival sandbox where other players are scarier than the zombies.

Execution · Grand Arena
Battle royale survival blending aim, rotation planning, and heavy circle-and-loot RNG.
DayZ leans Variance (Grand Arena); PUBG Mobile leans Execution (Grand Arena).
PUBG Mobile leans a little harder on execution, though the gap is small.
DayZ
gunfights punish slow hands severely
PUBG Mobile
Touchscreen aim and recoil control set the ceiling
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
PUBG Mobile
Outguessing rotations and third-party timing of human squads
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
DayZ
loot spawns and who you meet are unknowable
PUBG Mobile
Circle placement, loot and drop locations dominate single matches
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
DayZ
map knowledge and survival routines compound
PUBG Mobile
Zone rotation theory and loadout priorities are well mapped
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.