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

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

Execution · Competitive PvP
Football execution and human mind-games layered over tactical formation play.
FIFA Soccer 11 leans Execution (Competitive PvP); International Superstar Soccer Pro 98 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
International Superstar Soccer Pro 98
First-touch timing and finishing demand practiced hands
FIFA Soccer 11 leans a little harder on reads, though the gap is small.
FIFA Soccer 11
Human opponents' defensive habits and attacking patterns must be modelled
International Superstar Soccer Pro 98
Versus matches hinge on outguessing a human defender
FIFA Soccer 11 leans a little harder on variance, though the gap is small.
FIFA Soccer 11
Deflections and keeper behaviour add bounded chaos
International Superstar Soccer Pro 98
Bounces and deflections add bounded match 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
International Superstar Soccer Pro 98
Formations and set-piece routines have learnable best answers
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.