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
The fan-favourite sequel with harder levels and deeper secrets.
Buster Bros. leans Execution (Practiced Mastery); Donkey Kong Country 2: Diddy's Kong Quest 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
Donkey Kong Country 2: Diddy's Kong Quest
Demanding jump chains and animal-buddy 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
Donkey Kong Country 2: Diddy's Kong Quest
Fixed enemy patterns, no adaptation
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
Donkey Kong Country 2: Diddy's Kong Quest
Secret Lost World entrances hidden until found
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
Donkey Kong Country 2: Diddy's Kong Quest
Routes, DK coins, and bonuses fully mappable
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.