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

Execution · Pure Mechanics
A run-and-gun arcade shooter that is almost pure twitch execution.

Execution · Pure Mechanics
A classic 2D Mario platformer rewarding tight jump execution above all.
Metal Slug 5 leans Execution (Pure Mechanics); New Super Mario Bros. U Deluxe leans Execution (Pure Mechanics).
Metal Slug 5 leans a little harder on execution, though the gap is small.
Metal Slug 5
precise dodge/shoot run-and-gun demands
New Super Mario Bros. U Deluxe
precise jump and platforming execution
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Slug 5
enemy waves are fully scripted patterns
New Super Mario Bros. U Deluxe
fixed enemy patterns, no adaptation
Metal Slug 5 leans a little harder on variance, though the gap is small.
Metal Slug 5
minor drop and spawn randomness
New Super Mario Bros. U Deluxe
minor enemy placement randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Slug 5
weapon pickup and route memorization
New Super Mario Bros. U Deluxe
level routing for speed/collectibles
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.