EPUB is one of the world's most popular e-book formats. The name comes from the English phrase electronic publication. An ePUB book is actually an archive containing several folders. In one, the text of the book, in another, a description (author's name, title, publisher, language, identification number, etc.), in the third picture, in the fourth service information ... The reading program brings it all together and gives the reader the result in formatted text with illustrations, formulas, etc. The format is open - it can be modified by anyone.
The Portable Document Format (PDF) is a versatile file format that preserves the fonts, images, and layout of the original document, regardless of which of many platforms and which of many applications the document was created on. It was initiated by Adobe and was originally intended for electronic presentation of printed materials. PDFs look the same no matter what device they are viewed on. Whether you're using Windows 10, Mac, Chrome OS, Android, Windows Phone, iPad, or Windows XP - on any software or hardware, PDFs remain the same.