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
Classic licensed football testing input control and opponent pattern reading.

Execution · Competitive PvP
Shot timing and play-calling against opponents who scheme around your habits.
FIFA Soccer 2005 leans Execution (Competitive PvP); NBA 2K16 leans Execution (Competitive PvP).
FIFA Soccer 2005 leans a little harder on execution, though the gap is small.
FIFA Soccer 2005
Off-the-ball control and finishing timing are mechanical skill
NBA 2K16
Shot-stick timing and dribble moves gate every possession
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 2005
Human opponents adjust attack patterns across a match
NBA 2K16
Online opponents adjust defensive schemes against your tendencies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA Soccer 2005
Bounces and keeper behaviour add minor chaos
NBA 2K16
Shot RNG and card packs add bounded randomness
NBA 2K16 leans a little harder on optimization, though the gap is small.
FIFA Soccer 2005
Formations and exploit plays of the era are learnable
NBA 2K16
Playbooks, rotations and roster building reward deep 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.