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
Twin assassins seize Victorian London borough by borough with gang warfare and a rope launcher.

Optimization · Practiced Mastery
Rockstar's open-world schoolyard adventure about surviving a corrupt boarding school.
Assassin's Creed Syndicate leans Optimization (Practiced Mastery); Bully 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.
Assassin's Creed Syndicate
Rope-launcher traversal and simple brawling
Bully
Brawling and minigames take modest reflexes
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed Syndicate
Gangs are scripted
Bully
Schoolyard AI is scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed Syndicate
Fixed activities
Bully
Open world is largely deterministic
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed Syndicate
Gang upgrades and borough takeover planning
Bully
Class minigames, schedules, and mission routing reward 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.