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
Simon Belmont's SNES remake-quest with a multidirectional whip and a moody trek to Dracula.

Execution · Practiced Mastery
Arcade run-and-gun reflexes over memorised enemy placements.
Super Castlevania IV leans Execution (Practiced Mastery); Top Gunner 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.
Super Castlevania IV
Eight-way whip control and stair commitment test precision
Top Gunner
Dodging bullet streams in the jeep is pure arcade reflex
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Super Castlevania IV
Classic scripted monster patterns
Top Gunner
Enemy emplacements fire on fixed scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Super Castlevania IV
Hidden wall meat, fixed locations
Top Gunner
Layouts never change between credits
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Super Castlevania IV
Subweapon choice and boss pattern study
Top Gunner
Memorising spawn points and POW routes maximises score runs
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.