The main difference between the Kindle Fire and Nook Tablet is that the Nook Tablet weighs less and has slightly better battery life than the Kindle Fire but does not have access to the same level of cloud capabilities. Overall, the two devices are fairly evenly matched in most respects.
In terms of performance, both devices are very similar. The Nook and Kindle both have 8GB of storage capacity and both use the same processor, a 1Ghz dual core device, which makes them evenly matched when it comes to processing speed and storage space.
Both devices also use the Android OS, so there are no major differences in terms of software or app availability.
While both devices do offer cloud storage, the Kindle Fire has the advantage due to the fact that Amazon has a much wider amount of products and data on their cloud, compared to the smaller Barnes & Noble cloud. The Amazon cloud also offers free storage up to 5GB.
The Nook can make the better choice if a lighter, more mobile tablet is required, such as for someone who travels frequently, while the Kindle Fire's cloud access may better suit those with frequent Internet access.