It went from Black Box v2 to Eye Candy v3 to Eye Candy 4000. Each one is just an upgrade of the previous. You'll find that five filters have been added to the package. They include Marble, Wood, Drip, Melt and Corona. At first glance, you might think that some filters have been removed as they are no longer listed.
Nothing has been removed, it is just that some filters have been merged into a single filter.
All of the same options exist, just in a different form. If you read my review of KPT 6 a while back, you know I'm not a fan of that non-standard interface. And so I give major kudos to Eye Candy for sticking with a standard interface while adding a ton of functionality. A good example of the interface change is the addition of the Bevel Profile Editor to the Bevel Boss, Chrome and Glass filters. You've still got a list of the most used profiles, but now you can directly edit the curve of the bevel you want.