Hi Peter and welcome to the forums!
I removed Lua and Direct3D from Dry, and only run Linux myself. In my view Dry should remain cross-platform, but with FOSS operating systems as first-class citizens.
The main difference between the two engines is that LucKey projects still build using Dry and that it can be modified, whereas Urho3D diverged too much ever since its remaining developers started forming a clique that increasingly ignored the community and effectively threw a wrench into the works to draw people towards their fork.
Additions to Dry so far include (typed) polynomials, a wrapper for Bullet's kinematic character controller and dice rolls. Other features like support for block-based map filetypes, pre-made ragdolls, procedural geometry, a better particle system – utilizing polynomials – and sound synthesis modules are WIP outside the engine, intended to be included later. Dry's API is also a little more consistent. For instance String::IsEmpty() instead of Empty(), along with other minor changes of a similar nature.
Also, Urho3D lacks editors. Its only editor was written in AngelScript and, to quote the project's founder Lasse Öörni (aka Cadaver) "is somewhere halfway between a complex script API usage example, and a production-usable editor"; it's functional but honestly a hassle to work with.
Dry should improve on this with programs like ManaWarg, Edddy, Dolly and Garash.
