head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

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

Optimization · Practiced Mastery
Revenge-driven open-worlder dismantling a sixties crime empire district by district.
Mad Max leans Optimization (Practiced Mastery); Mafia III leans Optimization (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
Mafia III
Stealth takedowns and gunfights
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
Mafia III
Racket guards follow fixed 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
Mafia III
Open world is static
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mad Max
Magnum Opus upgrades and stronghold routing
Mafia III
District takeover loop and underboss assignments
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.