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
Shot timing and play-calling against opponents who scheme around your habits.

Execution · Competitive PvP
Reversal timing and grapple guessing games in a famously buggy wrestling package.
NBA 2K16 leans Execution (Competitive PvP); WWE 2K20 leans Execution (Competitive PvP).
NBA 2K16 leans a little harder on execution, though the gap is small.
NBA 2K16
Shot-stick timing and dribble moves gate every possession
WWE 2K20
Reversal timing windows decide matches but inputs stay forgiving
NBA 2K16 leans a little harder on reads, though the gap is small.
NBA 2K16
Online opponents adjust defensive schemes against your tendencies
WWE 2K20
Human opponents bait reversals and mix grapple choices
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K16
Shot RNG and card packs add bounded randomness
WWE 2K20
Notorious bugs add chaos; systems otherwise deterministic
NBA 2K16 leans a little harder on optimization, though the gap is small.
NBA 2K16
Playbooks, rotations and roster building reward deep study
WWE 2K20
Move-set knowledge and stamina management give an edge
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.