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
Action RPG prequel to FFVII whose combat spins a slot machine for buffs.

Optimization · Practiced Mastery
A tense survival horror where one bite kills your survivor for good.
Crisis Core: Final Fantasy VII leans Optimization (Practiced Mastery); ZombiU 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.
Crisis Core: Final Fantasy VII
real-time dodging and attack timing
ZombiU
Deliberate cricket-bat timing and panic inventory management
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Crisis Core: Final Fantasy VII
no adaptive opponent
ZombiU
Zombies shamble on fixed logic
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Crisis Core: Final Fantasy VII
DMW slot reels randomize limit breaks and levels
ZombiU
Permadeath runs face unknown spawn placements
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Crisis Core: Final Fantasy VII
materia fusion is a deep solvable system
ZombiU
Route knowledge, supply caching, safehouse 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.