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
Timing-based boxing with training preparation and opponent-specific weaknesses.

Execution · Competitive PvP
Reversal timing and pacing against an opponent baiting your counters.
Rocky leans Execution (Competitive PvP); WWE 2K15 leans Execution (Competitive PvP).
Rocky leans a little harder on execution, though the gap is small.
Rocky
Punch timing, blocking, and stamina control lead the test
WWE 2K15
Reversal timing windows decide most exchanges
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Rocky
Versus boxing rewards baiting and predicting a human opponent
WWE 2K15
Human opponents bait reversals and vary move timing
WWE 2K15 leans a little harder on variance, though the gap is small.
Rocky
Fights are mostly deterministic given inputs
WWE 2K15
Chain-wrestling rock-paper-scissors minigames add randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Rocky
Training stat allocation and opponent weaknesses reward prep
WWE 2K15
Move sets, stamina and match pacing are learnable systems
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.