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
Classic fighting execution and human prediction atop a famously unbalanced roster.

Execution · Competitive PvP
The toned-down crossover fighter matching Mortal Kombat's roster against DC superheroes.
Mortal Kombat Trilogy 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 Trilogy
Dial-a-combo inputs and run-meter pressure demand fast hands
Mortal Kombat vs. DC Universe
Juggle combos and klose kombat timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Kombat Trilogy
Human opponents must be baited into unsafe moves
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 Trilogy
Movesets are public; nothing hidden in a match
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 Trilogy
Knowing the bloated roster's broken tech is half the battle
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.