Traits apply to the note, while hooks apply to the hierarchy. While they have quite a bit of overlap, the difference is what happens when you move notes around. For example, a journal note is always a journal note even if you move it into a different hierarchy. But a hook will only apply to a specific hierarchy, so it won't apply if you move the note into a different hierarchy. Right now this distinction is not super important because hooks and traits only have the "onCreate" functions, but it will make a lot more difference once we expose more functionality.