The core difference between EPUB and MOBI is that EPUB is broadly supported on all platforms, while MOBI is mostly a Kindle format. The EPUB is open-source software and is maintained by the International Digital Publishing Forum (IDPF), a global standards and trade organization. And MOBI is an Abbreviation for Mobipocket e-book format and it is one of the early formats, It was bought and managed by Amazon.
EPUB is created by placing the files in a directory, A package of .xml file, an OPF file, and XHTML content files, and then zipping all together and using as .epub. filename extension. On the other side, MOBI is created by taking an EPUB file, renaming, zipping, and extracting and using kindlegen.exe which is a proprietary Amazon program.
MOBI is also a cross-platform and e-books in this format can have a .prc or .mobi extension. MOBI formats can handle complex content, contain advanced navigation controls, support indexing, and handle a high level of compression. For example, readers can add their own pages, freehand drawings, annotations, highlights, bookmarks, corrections, and notes if their devices support it. MOBI can also contain a dictionary. Because of the 64k image size limitation unlike larger display devices like tablets, the MOBI format is best suited for smaller screens as well. Like EPUB, MOBI can display both reflowable content and a fixed-width layout.
Used by many experts as the most common of all formats, .epub is largely compatible with all platforms, which is why most electronic reading devices and apps such as Apple iBooks, Adobe Digital Editions, Aldiko on Android, Barnes & Noble’s Nook, etc. supports .epub files. Amazon Kindle is the only exception, which does not yet support .epub files. The EPUB format is an open standard. That means it is free and publicly available, although there are certain rules for its usage. EPUB can display “Reflowable” content that will fit your presentation to the output devices, as well as a fixed-width layout. It is very similar in appearance to HTML-rendered pages with images.