The largest advantage the original Nook has over the original Kindle is significantly more storage capacity; Nook has 2 GB while the Kindle only has 256 MB or .256 GB. However, the original Kindle is slightly lighter than the original Nook, at 10.3 ounces versus 11.2 ounces.
Each e-reader has a high definition version. The main benefit of the Kindle Fire HD, as opposed to the Nook HD, is that the former has a front-facing camera. The Nook HD is lighter and slightly less expensive, because the $20 wall charger is included with the Nook, as of 2015. The Kindle Fire HD also has better audio with Dolby speakers.
The Kindle and Nook also come in light-up versions: the Kindle Paperwhite and the Nook Glowlight. Because the Paperwhite uses a newer version of the light-up technology than the Glowlight, it has a bit more contrast and the background is lighter, making the Paperwhite easier to read than the Glowlight.
The Kindle Paperwhite's EasyReach tap zones make turning pages easier than the Nook because the left thumb can tap rather than swipe to turn pages. The Nook's page turning software does not work as well with both hands. The Paperwhite also has many more extra features for readers than the Nook version. Both give readers the ability to look up words in a dictionary and loan e-books to other readers for up to two weeks. The Kindle also lets users export notes and highlights or copy and paste these notes from another web interface.