head to head
FIFA Soccer 08 asks more than Tennis World Tour 2, and the gap is reads.

Execution · Competitive PvP
Stick execution and outguessing a human defender, with tactics underneath.

Execution · Pure Mechanics
A tennis simulation testing shot execution and reading opponent positioning.
FIFA Soccer 08 leans Execution (Competitive PvP); Tennis World Tour 2 leans Execution (Pure Mechanics).
Tennis World Tour 2 leans a little harder on execution, though the gap is small.
FIFA Soccer 08
Dribbling, timing tackles and finishing reward stick skill
Tennis World Tour 2
shot timing, positioning, and precision control
FIFA Soccer 08 leans clearly harder on reads.
FIFA Soccer 08
Versus humans, baiting defenders and disguising attacks is core
Tennis World Tour 2
human opponents adapt shot placement
FIFA Soccer 08 leans a little harder on variance, though the gap is small.
FIFA Soccer 08
Ball physics adds bounce noise to single matches
Tennis World Tour 2
minor ball-physics unpredictability
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 08
Formations and squad selection matter but stay shallow
Tennis World Tour 2
minor player/equipment choice
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.