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
A driving sim testing smooth vehicle handling against timetables and traffic rules.

Optimization · Practiced Mastery
Revenge-driven open-worlder dismantling a sixties crime empire district by district.
Bus Driver 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.
Bus Driver
Smooth braking and lane discipline are the physical test
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.
Bus Driver
Traffic follows predictable scripted rules
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.
Bus Driver
Routes and conditions are set per scenario
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.
Bus Driver
Timetable adherence and rule-following decide the score
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.