In many ways, Apocalypse World has a lot of definition. There's a fixed list of stats, and a fixed set of playbooks, each with predetermined moves to select from. Lots of the details of the world are open to the MC, and also to the characters as they answer the MC's questions and flesh out the world in their interactions. But, on some level, a gun's a gun. You can make choices that determine whether or not you get shot at, you can roll well or badly to determine whether you get shot, but you can't transcend the risk of guns. Like in a no-weirdshit Guild spygame, if you get shot, you're shot, and if you get shot enough, you're dead, for well-defined values of "enough". These world constraints combined with the well-defined dice mechanics leads to situations with clear, finite choices with clear, predictable consequences.
Chuubo's is a lot different. What character types there are are manifestly optional, and the free choice of skills and afflictions makes characters very open-ended, even at the mortal level. There's no particular constraint on the characters that an affliction or skill couldn't be used to circumvent (though the HG could forbid it, of course). (With miraculous arcs, character ability to transcend or reconceptualize things gets even more extreme.) Various narrative actions also give players more of a role in actively setting the terms of a scene. It in some ways moves the focus more on the characters and less on the situation, and is somewhat reminiscent of high-weirdshit Guild games where someone might be unexpectedly bulletproof, or even have an open-ended player-creativity-based power. While player choices still drive the narrative, it's less choosing well-defined tradeoffs in a constrained world and more about creatively creating options and making choices based on narrative or character development factors.
I find it interesting that, despite both games being narratively-focused "play to see what happens" games, they actually seem quite different to me on this axis, and this affects the feel of the gameplay greatly. I seem to be conceptualizing Librarians as somewhere in-between. We'll see where it ends up if anything ever comes of it.