Other hardware features include, integrated 8 GB of internal memory and an SD card slot, upgrading the memory to up to 32 GB. (goodereader.com)
But in addition to the really obvious differences between these two new flagships — like the taller 18:9 aspect ratio of the Pro — there are a handful of other hardware differences worth noting. (androidcentral.com)
Choice of hardware to access books (e.g. in 3 years when your device has broken, you can still read your book on other hardware) 5. (ebookevangelist.com)