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
A tactical shooter where precise gunplay against human opposition is the deciding skill.

Execution · Competitive PvP
Stick execution and opponent reading within football's bounded chaos.
Counter-Strike: Condition Zero leans Execution (Competitive PvP); FIFA 15 leans Execution (Competitive PvP).
Counter-Strike: Condition Zero leans a little harder on execution, though the gap is small.
Counter-Strike: Condition Zero
aim and spray control decide duels
FIFA 15
Dribble and shot timing decide most online matches
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Counter-Strike: Condition Zero
predicting human opponent positioning
FIFA 15
Human opponents adapt formations and bait your defending
FIFA 15 leans a little harder on variance, though the gap is small.
Counter-Strike: Condition Zero
buy-round economy and drops vary slightly
FIFA 15
Deflections and bounce physics swing single matches
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Counter-Strike: Condition Zero
economy management and utility usage solvable
FIFA 15
Squad building and meta tactics reward dedicated 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.