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

Execution · Practiced Mastery
A fast mech-action game where assembling the right build and piloting it hard both decide bosses.

Execution · Practiced Mastery
Precise car control married to tuning and racing-line study.
Armored Core VI: Fires of Rubicon leans Execution (Practiced Mastery); Forza Motorsport 3 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.
Armored Core VI: Fires of Rubicon
Boss fights demand sharp dodges and stagger timing
Forza Motorsport 3
Braking points and throttle control define lap times
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Armored Core VI: Fires of Rubicon
Campaign bosses are scripted; PvP is niche
Forza Motorsport 3
AI drivers follow predictable racing lines
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Armored Core VI: Fires of Rubicon
Fixed encounters
Forza Motorsport 3
Clean circuit racing leaves little to chance
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Armored Core VI: Fires of Rubicon
Build crafting trivializes many bosses
Forza Motorsport 3
Tuning, upgrades and line study are half the lap time
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.