head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
A licensed brawler testing spacing and pattern memorisation through fixed stages.

Execution · Practiced Mastery
Precision sniping and arena navigation through fixed, gimmick-laden levels.
Batman Returns leans Execution (Practiced Mastery); MDK leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Batman Returns
Crowd control spacing and boss timing carry the game
MDK
Sniper-mode precision and arena dodging demand steady hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Batman Returns
Clowns attack in fixed waves
MDK
Alien enemies behave on fixed scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Batman Returns
Stages never change between attempts
MDK
Levels are authored with nothing random
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Batman Returns
Learning enemy waves and item spots is the depth
MDK
Learning arena gimmicks and item use solves each level
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.