Most of the Quran books are printed in China like all things nowadays, so the question is what is the difference between throwing some printed Quran book (Made in China) in the trash can and deleting a Quran ebook from some cloud storage or an ftp etc. Any eArabs here?
The difference is that when in hard copy, throwing it somewhere unclean means that it can later be seen there, which is irrespectable to the Holy Qur'an. But when deleted from an electronic storage, it doesn't go anywhere at all, it just vanishes.
Think about when you have to throw something away that has Qur'anic phrase in it. You're highly encouraged to burn them, instead of throwing them in bare. Burning "wipes" away the saying of Allah and so it won't be seen in an unpleasant condition later. I would say deleting an e-book is just like the burning.
First, a better answer could be given by non-Arab. Arab is a race or rather a panethnic group, while Islam is a religion in which one of the main concepts is no racial discrimintation. In regards to the question, the idea is to respect the book of Allah. Some muslimes do memorize Quran in their minds and they forget it after a while. It's similar to storing it on CD or cloud or what so ever. However, when it is in a hardbook, muslims are strongly advised to deal with it with all respect as a symbol of Allah fearing.