File represented by .ONE extension are created by Microsoft OneNote application. OneNote lets you gather information using the application as if you are using your draftpad for taking notes. OneNote files can contain different elements that can be placed at non-fixed locations on document pages. These elements may contain text, digitized handwriting, and objects copied from other applications including images, drawings and multimedia (audio/video) clips.
A file with .emz extension is a compressed container of Enhanced Metafile (.emf file). It follows .GZIP compression algorithm and takes less storage space due to compression. The small file size makes it more easy to transfer EMZ files over the network.
You can also convert ONE into many other file formats. Please see the complete list below.