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
A rugby sim testing on-field execution and tactical play-calling.
NBA 2K14 leans Execution (Competitive PvP); Rugby 08 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
Rugby 08
Timing tackles, passes and kicks needs manual skill
NBA 2K14 leans a little harder on reads, though the gap is small.
NBA 2K14
Online opponents counter your favourite plays
Rugby 08
Human opponents bluff plays; AI is scripted
Rugby 08 leans a little harder on variance, though the gap is small.
NBA 2K14
Shot RNG sways close possessions
Rugby 08
Some randomness in tackle and bounce outcomes
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
Rugby 08
Play calling and team tactics are a learnable layer
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.