head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Execution · Competitive PvP
The peak-era Konami football game prized for weighty, skill-driven match play.

Execution · Competitive PvP
An anime fighting game testing execution and prediction against human opponents.
Pro Evolution Soccer 6 leans Execution (Competitive PvP); Yu Yu Hakusho: Ghost Files - Dark Tournament leans Execution (Competitive PvP).
Pro Evolution Soccer 6 leans a little harder on execution, though the gap is small.
Pro Evolution Soccer 6
First touch, through balls, and dribbles demand precise control
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.
Pro Evolution Soccer 6
Versus matches are constant feint and positioning prediction
Yu Yu Hakusho: Ghost Files - Dark Tournament
Human versus opponents drives prediction of attacks and blocks
Yu Yu Hakusho: Ghost Files - Dark Tournament leans a little harder on variance, though the gap is small.
Pro Evolution Soccer 6
Deflections and keeper spills add light randomness
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.
Pro Evolution Soccer 6
Formations and player roles are studyable
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.