This article explains that ePubs are a form of eBooks. Unlike PDFs, ePubs have the ability to adapt to different screen sizes. This makes reading text in ePub format much more user friendly.
Why won’t the ePub open on my computer?
The PDF opens easily on the computer, why doesn’t the ePub? The ePub will open if the computer has an application to open ePubs, but might lose some of the functionality available on the iPad. A common computer application is Calibre. It’s a free download at http://calibre-ebook.com.
Remember the ePub opens easily on your iPad!
Are PDFs and ePubs the same in iBooks?
The iBook app can read PDF and ePubs but they don’t behave the same. It’s easy to search for text in either format, and the text can be bookmarked. The ePub turns pages instead of simply sliding from one page to the next. Text in an ePub can be selected and a note added.
What’s a book app?
Some books are an app rather than an eBook. They are not read by iBooks or another app reader, but simply read directly on the iPad. Book apps are often a delightful combination of graphics and interaction. Try Bats Furry Fliers of the Night if you want to fly through the night and test how their sonar works.