I barely tried Litestep once and it wasn't for me. It required too much playing around with stuff, whereas with DX you can often just use stuff others made and away you go.
However one important difference between the two I am aware of is that Litestep is a shell replacement and DX is a shell add-on. DX does not replace the explorer shell, it just works with it to provide more functionality.
Much of what can be accomplished with Litestep can be done with DX. DX is probably easier for the average person to work with.
A more detailed comparison though I cannot provide.

Hello Phar0e, I myself had used Litestep extensively in the past (since it was B23). And I have used DesktopX for a while and here is what I think.

There are things in desktopX that you would normally do in Litestep by coding say... an LS box simply by creating the shortcuts on your desktop, and grouping them from a right click. Like for example if you want to make a floating MP3 controlling object that remembers it's position. And the same for making objects that toggle each other. And you can easily package up different parts of the theme to distribute independently. However, to me at least there are objects that are quite difficult to change unless you are versed in things like vbscript. But DesktopX seems to have more things configurable with a GUI where you would have to code your own in Listestep.

DesktopX seems to take more advantage of transparency as it always has. It's a very nice program, however it doesn't replace you shell as was mentioned it adds to it, so there's no reason why you'd have to ditch Litestep to use DesktopX. In fact there was a time when I was using both as however it seems to me that DesktopX isn't the program that is meant to make bars such as taskbars\menubars, etc.

So I would say that DesktopX could complement either Explorer, or Litestep. Some people I have seen run a bare bones litestep setup so they can have in essence desktopX running as their shell.

I believe I will give it a shot. Thanks for the suggestion BoXXi, converting an existing theme of mine makes sense.

Can anyone tell me if there is a DX equivilent to the Litestep popup menu?

If you set DX to hide desktop icons, when you right-click on the desktop, it's a generic menu very similar to litesteps, but I don't think you can skin it or customize it. It's just built into DX, would be cool if ya could though...

I agree with Paxx. I used DX and OB all the time. I like gef's DX themes, though I do find that OB tends to be redundant. But sometimes the convenience of one over the other, when I have both, is very helpful.
I don't use Litestep, mostly because I don't feel like paying for yet another program, so I cannot comment on that.