Doesn't make much sense to refer to OneNote here, although both applications serve a similar purpose.
But as Evernote is based on a database (afaik), OneNote is based on file and folder structures on the storage level (even when the notebooks are stored on OneDrive, where the OneNote files are hidden except for a URL link file). In the original OneNote format notebooks are simple folders in the file system, sections are files (with the .ONE extension) that hold all pages and subpages in an object centered format based on XML. So it's natural for OneNote to use a hierachy, but lacks 1-to-n