head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Competitive PvP
Reversal-timing duels where reading a human opponent's pacing decides matches.

Execution · Competitive PvP
Reversal-timing duels where humans bait each other inside scripted spectacle.
WWE 2K16 leans Execution (Competitive PvP); WWE SmackDown vs. Raw 2011 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.
WWE 2K16
Reversal timing windows are the core physical test
WWE SmackDown vs. Raw 2011
Reversal timing windows reward practiced reactions
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
WWE 2K16
Human opponents bait reversals and vary move timing
WWE SmackDown vs. Raw 2011
Versus humans, reversal baiting becomes a guessing duel
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
WWE 2K16
Some grapple and AI randomness colours matches
WWE SmackDown vs. Raw 2011
Momentum swings and AI quirks add mild chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
WWE 2K16
Move-set knowledge and match pacing are learnable systems
WWE SmackDown vs. Raw 2011
Move sets, match types and creation systems are learnable
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.