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
The Deadly Alliance follow-up adding combo breakers, death traps, and online play.

Execution · Competitive PvP
The toned-down crossover fighter matching Mortal Kombat's roster against DC superheroes.
Mortal Kombat: Deception leans Execution (Competitive PvP); Mortal Kombat vs. DC Universe 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.
Mortal Kombat: Deception
Style strings plus stage-hazard spacing demand control
Mortal Kombat vs. DC Universe
Juggle combos and klose kombat timing
Mortal Kombat: Deception leans a little harder on reads, though the gap is small.
Mortal Kombat: Deception
Human opponents bait death traps and breakers
Mortal Kombat vs. DC Universe
Human mixups, though a simpler toolset than peers
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat: Deception
Deterministic outside known stage hazards
Mortal Kombat vs. DC Universe
Deterministic crossover combat
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat: Deception
Combo routes and hazard positioning are lab work
Mortal Kombat vs. DC Universe
Mapping juggle routes and matchup tools rewards practice
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.