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 · Practiced Mastery
Stick execution and opponent prediction over a franchise-management layer.

Execution · Competitive PvP
Execution on the ball plus constant prediction of the other player's shape.
NHL 2K6 leans Execution (Practiced Mastery); Pro Evolution Soccer 2009 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.
NHL 2K6
Shot timing, dekes and poke checks decide possessions
Pro Evolution Soccer 2009
Close control and finishing windows demand stick precision
Pro Evolution Soccer 2009 leans a little harder on reads, though the gap is small.
NHL 2K6
Human opponents disguise plays and bait pulls online
Pro Evolution Soccer 2009
Online and couch opponents adjust tactics against you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
NHL 2K6
Rebounds and deflections add per-game noise
Pro Evolution Soccer 2009
Ricochets and keeper parries add small randomness
NHL 2K6 leans a little harder on optimization, though the gap is small.
NHL 2K6
Line management and franchise decisions reward planning
Pro Evolution Soccer 2009
Squad setup and tactical sliders reward preparation
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.