Paperwhite is really LIGHT.
Just to see how the weights compare I weighed my 3 Kindles inside their covers. This is how it turned out:
Kindle Kbd WiFi 3rd Gen = 13.5 ounces
Kindle Paperwhite WiFi = 11.8 ounces
Kindle Fire 7" 1st Gen = 1 pound, 4.0 ounces
The Paperwhite is really light and easy to hold sitting in a chair without any desk or table. The Kindle Fire really needs to be placed on a desk in its stand and not held.
For just reading eBooks the Paperwhite wins hands down. For running Android Apps, watching TV and listening to music the Kindle Fire is best.