It is "just like any other tablet" except that it is "tied" to Amazon.
So Amazon want you to buy one, then use it to download films, music and books from their web site.
It does run Android software, same as the the Samsung Galaxy and Google Nexus, but Amazon has tailored the interface so it works closer to their Amazon web site.
If you buy the cheaper one "with special offers" then you get Amazon adverts on the tablet.
p.s. I dont have a Kindle Fire but I believe you cant download things from the Android App Store (though willing to be proved wrong if someone else knows better)