OpenSCAD works natively with triangle meshes. sphere() will create a spherical triangle mesh.

These libraries on the other hand can natively represent a sphere for instance. This means that during CAD-ing you don't need to worry about resolution, that's a consideration for export only.

Do you mean that OpenScad performs boolean/other operations on triangle meshes, but these libraries don't until output? So they might instead use curved surfaces/edges etc as outputs for operations and only convert to triangles for output or export at the very end?