Files with .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 .TXT extension represents a text document that contains plain text in the form of lines. Paragraphs in a text document are recognized by carriage returns and are used for better arrangement of file contents. A standard text document can be opened in any text editor or word processing application on different operating systems. All the text contained in such a file is in human-readable format and represented by sequence of characters.
You can also convert ONE into many other file formats. Please see the complete list below.