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.
PPSX, Power Point Slide Show, file are created using Microsoft PowerPoint 2007 and above for Slide Show purpose. It is an update to the PPS file format that was supported by Microsoft PowerPoint 97-2003 versions. When a PPSX file is shared with another user and opened, it starts as PowerPoint show unlike PPTX file that opens in editable mode. The sequence of slide show is the same as in the original presentation. All the slides accompany the images, sounds and other embedded media accompany the presentation slides to the PPSX during the slideshow.
You can also convert ONE into many other file formats. Please see the complete list below.