An electronic book, also known as an e-book or eBook, is a
book publication made available in digital form, consisting
of text, images, or both, readable on the flat-panel display
of computers or other electronic devices. Although sometimes
defined as "an electronic version of a printed book", some
e-books exist without a printed equivalent. E-books can be
read on dedicated e-reader devices, but also on any computer
device that features a controllable viewing screen,
including desktop computers, laptops, tablets and
smartphones. The advantages of E-Books are many.
An audiobook (or a talking book) is a recording of a book or
other work being read out loud. A reading of the complete
text is described as "unabridged", while readings of a
shorter version are an abridgement.
You don't have to keep all the E-books and Audiobooks you have
purchased (and downloaded) on your devices. You can delete the
ones you are not currently reading (or listening to) and
re-download later as necessary.
Good houseking practice--get it off of your devices when
finished reading or listening.