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
Shot timing and play selection against opponents adjusting to your tendencies.

Execution · Practiced Mastery
Stick execution and opponent prediction over a franchise-management layer.
NBA 2K14 leans Execution (Competitive PvP); NHL 2K6 leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K14
Shot release timing and dribble chains gate scoring
NHL 2K6
Shot timing, dekes and poke checks decide possessions
NBA 2K14 leans a little harder on reads, though the gap is small.
NBA 2K14
Online opponents counter your favourite plays
NHL 2K6
Human opponents disguise plays and bait pulls online
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K14
Shot RNG sways close possessions
NHL 2K6
Rebounds and deflections add per-game noise
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K14
Playbook knowledge and roster management reward study
NHL 2K6
Line management and franchise decisions reward planning
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.