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
Fast arena-fighter execution plus guessing games against a human opponent.

Execution · Competitive PvP
A boxing game testing punch timing and reading opponent openings.
Dragon Ball Z: Budokai Tenkaichi 3 leans Execution (Competitive PvP); Real Boxing leans Execution (Competitive PvP).
Real Boxing leans a little harder on execution, though the gap is small.
Dragon Ball Z: Budokai Tenkaichi 3
Combo timing, dashes and beam clashes demand fast hands
Real Boxing
Timing punches, blocks and dodges is the core
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon Ball Z: Budokai Tenkaichi 3
Versus humans, baiting counters and vanish wars is prediction
Real Boxing
Reading opponent feints matters in multiplayer
Real Boxing leans a little harder on variance, though the gap is small.
Dragon Ball Z: Budokai Tenkaichi 3
Almost nothing hidden once both rosters are known
Real Boxing
Little randomness in outcomes
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon Ball Z: Budokai Tenkaichi 3
Character tiers and combo routes form a learnable layer
Real Boxing
Stat training and stamina management add depth
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.