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 · Practiced Mastery
Wasteland open-worlder upgrading one car to conquer scripted scrap territories.

Execution · Practiced Mastery
Loose action execution and horde-building through scripted comedy set-pieces.
Mad Max leans Optimization (Practiced Mastery); Stubbs the Zombie in Rebel Without a Pulse leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mad Max
Car combat and counter-brawling timing
Stubbs the Zombie in Rebel Without a Pulse
Limb-throwing and horde wrangling need only loose aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mad Max
War boys follow fixed AI
Stubbs the Zombie in Rebel Without a Pulse
Townsfolk and soldiers follow scripted AI
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mad Max
Open world is static once scouted
Stubbs the Zombie in Rebel Without a Pulse
Encounters are fixed set-pieces
Mad Max leans a little harder on optimization, though the gap is small.
Mad Max
Magnum Opus upgrades and stronghold routing
Stubbs the Zombie in Rebel Without a Pulse
Conversion economy - building your horde - rewards light planning
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.