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

Execution · Competitive PvP
Football sim testing stick execution and reading a human opponent's tactical habits.

Execution · Competitive PvP
An anime fighting game testing execution and prediction against human opponents.
FIFA Soccer 11 leans Execution (Competitive PvP); Yu Yu Hakusho: Ghost Files - Dark Tournament leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 11
Pass timing, dribbling and finishing demand stick skill
Yu Yu Hakusho: Ghost Files - Dark Tournament
Combo timing and spacing matter in fast 2D fights
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 11
Human opponents' defensive habits and attacking patterns must be modelled
Yu Yu Hakusho: Ghost Files - Dark Tournament
Human versus opponents drives prediction of attacks and blocks
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 11
Deflections and keeper behaviour add bounded chaos
Yu Yu Hakusho: Ghost Files - Dark Tournament
Some card-mode RNG and matchup chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 11
Formations, tactics and squad knowledge shape matches
Yu Yu Hakusho: Ghost Files - Dark Tournament
Character movesets and matchups reward study
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.