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.
Files with ODP extension represent presentation file format used by OpenOffice.org in the OASISOpen standard. A presentation file is a collection of slides where each slide can comprise of text, images, formatting, animations, and other media. These slides are presented to audience in the form of slideshows with custom presentation settings.
You can also convert ONE into many other file formats. Please see the complete list below.