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
Arcade positioning and pop-order planning against deterministic bouncing balloons.

Execution · Practiced Mastery
Retro ninja platformer that flips from linear levels into a time-hopping metroidvania.
Buster Bros. leans Execution (Practiced Mastery); The Messenger 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.
Buster Bros.
Dodging splitting balloons while firing demands precise positioning
The Messenger
cloudstep chains demand precise aerial control
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Buster Bros.
Balloons bounce on pure deterministic physics
The Messenger
enemies and bosses are fully scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Buster Bros.
Weapon drops vary slightly per clear
The Messenger
deterministic level design
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Buster Bros.
Optimal pop order per fixed stage layout is learnable
The Messenger
upgrade economy and late-game route knowledge
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.