With the "special offer" it's with advertising (it can be removed after purchase by paying a limited amount), and without the special offer it's the model without advertising.

The difference between "Special Offer" (with adverts) and "Non Special Offer" (without adverts) on this eReader is that the Special Offer version displays adverts on the lock screen, which you have to wipe away when you switch on the device. The Non Special Offer version is ad-free, so it does not display adverts on the lock screen, which ensures an undisturbed reading experience. You usually pay a surcharge for the ad-free version or can have the adverts removed later for a fee.