Any electronic book can be called an eBook, but because over 90% of all eBooks are read on Amazon’s Kindle, Apple’s iOS devices (iPad, iPhone and iPod) and the Barnes & Noble Nook, I’ll focus on the formats for those platforms:
This is an open standard adopted by Apple (iOS), Barnes & Noble (Nook) and many other makers of eBook readers (such as Sony)
EPUB was truly designed to display text, possibly with some inline images. While creating an EPUB illustrated children’s book, comic book, travel book or cookbook is possible, it’s a lot more work and doesn’t work very consistently across platforms. A good rule of thumb is that eBooks are best for books with a lot of words (think New York Times bestseller list).
This is a proprietary format that Amazon uses for its Kindle, which is a modification of the Mobipocket format.
PDF is inherently made for print and doesn’t display well on digital devices. But if you really need to get data out to an iOS or Android device now, then it’s a useful format. Kindle DOES support PDF
eBook Maker and eBook Maker for Mac can help you build your own eBooks from 10+ popular formats(.doc, .pdf, .html, .txt, .chm, etc) with ease.