The external casing on the Lilliput is smaller than the external casing of both the older and latest generation Xenarcs. The Lilliput I borrowed fit behind my dash with about 3-4mm each side, the new Xenarc was a perfect fit, and the older Xenarc was about 2-3mm too big either side.
As for screen sizes, I can't help you there, I haven't taken apart the Lilliput or newer Xenarc, and didn't measure the older Xenarc when I had it apart.
Hope this helps a little
Garry