head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Competitive PvP
Fast arena-fighter execution plus guessing games against a human opponent.

Execution · Competitive PvP
The Deadly Alliance follow-up adding combo breakers, death traps, and online play.
Dragon Ball Z: Budokai Tenkaichi 3 leans Execution (Competitive PvP); Mortal Kombat: Deception 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 3
Combo timing, dashes and beam clashes demand fast hands
Mortal Kombat: Deception
Style strings plus stage-hazard spacing demand control
Mortal Kombat: Deception leans a little harder on reads, though the gap is small.
Dragon Ball Z: Budokai Tenkaichi 3
Versus humans, baiting counters and vanish wars is prediction
Mortal Kombat: Deception
Human opponents bait death traps and breakers
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 3
Almost nothing hidden once both rosters are known
Mortal Kombat: Deception
Deterministic outside known stage hazards
Mortal Kombat: Deception leans a little harder on optimization, though the gap is small.
Dragon Ball Z: Budokai Tenkaichi 3
Character tiers and combo routes form a learnable layer
Mortal Kombat: Deception
Combo routes and hazard positioning are lab work
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.