Groups vs notebooks

I'm working on a note taking app. One of the feature is that you can group the notes in a folder like manner in which one can create. subgroups inside groups and more subgroups and put notes/notebooks inside it. The app has also a feature where the user can make notebooks in which the user can add notes (You cannot put a notebook inside a notebook). But doesn't that make the notebook same as a group without subgroups? How useful this feature can be? Can having both confuse people? Thank You.

Edit:

It already has hashtagging so one can link notes regardless of grouping. The smallest unit is called a "note" (there are different kinds of notes). Currently, you can put a note inside a "notebook" and/or a group. There is nothing beyond "notebooks" but groups. The question here is if I should call a group of notes "notebook" when the user could just group the notes without the whole notebook thing. A bunch of note taking apps lets you group the notes into groups/folders and/or notebooks and I've always found it confusing. But I doubt if there is an actual point in being able to do this.