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
Wrestling-style timing duels with grapple prediction against human opponents.

Execution · Competitive PvP
Arena-fighter execution and couch-versus prediction across an enormous anime roster.
Def Jam Vendetta leans Execution (Competitive PvP); Dragon Ball Z: Budokai Tenkaichi 2 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.
Def Jam Vendetta
Grapple timing and reversal windows demand sharp inputs
Dragon Ball Z: Budokai Tenkaichi 2
Beam clashes, vanish timing and arena movement reward fast hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Def Jam Vendetta
Human matches turn on predicting grapples versus strikes
Dragon Ball Z: Budokai Tenkaichi 2
Versus friends, baiting transformations and dodges matters
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Def Jam Vendetta
Nothing hidden once movesets are learned
Dragon Ball Z: Budokai Tenkaichi 2
Full movesets are public knowledge
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Def Jam Vendetta
Character move pools and reversal systems are mappable
Dragon Ball Z: Budokai Tenkaichi 2
A 120-character roster of matchup and item knowledge
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.