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
Fast arena combat that tests combo execution and counter prediction against human opponents.

Execution · Competitive PvP
Analog-stick boxing testing punch precision and counter-baiting against human opponents.
Dragon Ball Z: Budokai Tenkaichi leans Execution (Competitive PvP); Fight Night 2004 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.
Dragon Ball Z: Budokai Tenkaichi
Combo timing, dashes and beam clashes reward fast hands
Fight Night 2004
Analog punch control and block timing are the core test
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
Versus humans, predicting teleport counters and ki tactics matters
Fight Night 2004
Versus humans, baiting counters and feinting is genuine prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon Ball Z: Budokai Tenkaichi
Almost nothing random once movesets are known
Fight Night 2004
Outcomes follow inputs with little randomness
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
Character matchups and attribute builds are learnable systems
Fight Night 2004
Stat training and stamina management add a planning layer
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.