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

Execution · Practiced Mastery
A football sim testing play execution and play-calling prediction against opponents.

Execution · Competitive PvP
Shot timing and play-calling against opponents who scheme around your habits.
Madden Football 64 leans Execution (Practiced Mastery); NBA 2K16 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.
Madden Football 64
Throw and run timing decides plays in real time
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.
Madden Football 64
Human opponents disguise plays, demanding prediction
NBA 2K16
Online opponents adjust defensive schemes against your tendencies
Madden Football 64 leans a little harder on variance, though the gap is small.
Madden Football 64
Catch and fumble outcomes carry simulated randomness
NBA 2K16
Shot RNG and card packs add bounded randomness
Madden Football 64 leans a little harder on optimization, though the gap is small.
Madden Football 64
Playbook, audibles and roster tactics run deep
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.