What is the difference between a Boost X and a regular Boost?

What is the difference between a carbonology Boost X and Boost? LV ??

I have paddled both in the last week.

In short the Boost X has surf leash point in the footwell, water bottle holder under the knees and the most noticeable difference was the seat shape. The back of the seat rake out the top top of the hull rather than a more vertical profile. Being a tall buy it made it a lot more comfortable for me as I didn't feel it was pushing into my back.  

The Boost LV is a lower volume version of the Boost. I believe the deck has been lowered on the LV but I think the hull is the same as the standard Boost. The LV has a smaller cockpit which obviously fits smaller bums better and holds less water in the event of fooding.
The X label is a commemoration of Carbonology Sport's 10th year of making surf skis. It also signifies some improvements to their existing designs some of which were mentioned by natana. In the case of the Boost & Boost LV (now called the Boost X and Boost LV X) I believe the rudder has been moved a bit further forward which should improve their already very good downwind performance.