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
Stick-skill football execution with opponent prediction in versus play.

Execution · Competitive PvP
Reversal timing and pacing against an opponent baiting your counters.
UEFA Euro 2008 leans Execution (Competitive PvP); WWE 2K15 leans Execution (Competitive PvP).
UEFA Euro 2008 leans a little harder on execution, though the gap is small.
UEFA Euro 2008
Pass timing, dribbling and finishing decide matches
WWE 2K15
Reversal timing windows decide most exchanges
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
UEFA Euro 2008
Versus humans, baiting tackles and disguising attacks matters
WWE 2K15
Human opponents bait reversals and vary move timing
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
UEFA Euro 2008
Bounces and deflections add football's usual noise
WWE 2K15
Chain-wrestling rock-paper-scissors minigames add randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
UEFA Euro 2008
Formations and squad selection sit underneath
WWE 2K15
Move sets, stamina and match pacing are learnable systems
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.