head to head
vs
Bullet Heaven 2vsGhosts 'n Goblins
Bullet Heaven 2 leans Execution (Pure Mechanics); Ghosts 'n Goblins leans Execution (Pure Mechanics).
Bullet Heaven 2Ghosts 'n Goblins
Axis by axis
Execution9 vs 9
Even - both lean on execution about the same.
Reads0 vs 0
Even - both lean on reads about the same.
Variance2 vs 1
Bullet Heaven 2 leans harder on variance: Item drops add minor randomness
Optimization5 vs 6
Ghosts 'n Goblins leans harder on optimization: Weapon choice and route memorisation are mandatory
Two games can score the same on an axis and still test it in very different ways - read each rationale, not just the number.