Also, because the link uses Amazon's internal shortcuts for memorable pages.
"kindlesoftwareupdates" and "paperwhite2"
paperwhite2 -- apparently someone at Amazon agrees with our classification system.
...
The reason you asked us was, of course, because Amazon does NOT give you any way of knowing which generation your Kindle is based on something easily distinguishable like serial numbers.
But now you know my secret.
http://amazon.com/kindlesoftwareupdates -- the landing page for all Kindles.
Append /touch or /paperwhite or /kindledx or similar to get specific models. I had to play around with different possibilities and not all the newer models got a special link (does the linky guy not work there anymore???) but it is pretty handy.