PDF (Portable Document Format) is a versatile electronic document format. It was initiated by Adobe and was originally intended for electronic presentation of printed materials. Hence, the tasks of this format follow - storing information about the color scheme and the arrangement of elements, as well as ensuring identical output on different monitors and printers. PDF documents can be opened using the free version of Adobe Reader or a web plug-in that is available for most Internet browsers. In some browsers, in particular, in Google Chrome, this format is supported even without the plugin installed. You can edit PDF files using the paid version of Adobe Reader. Also, there are a huge number of programs for both opening and working with this format, and for converting to other formats.
EPUB is a file format used to store e-books and other types of content. Developed by the International Digital Publishing Association. If you saw the EPUB format on the Internet, know that this is electronic content that is opened using special software. It is freely used on both computers and smartphones, tablets or e-books. Basically, an EPUB file is one or more HTML pages with saved images and styles. All this economy is packed in a ZIP archive, the extension of which has been replaced by epub. However, simply renaming the archive is still not enough. For it to be considered a full-fledged e-book, it must contain two service files: containing special container xml tags and including a list of all content.opf objects included in the e-book.