Originally posted by GUB DT is purely and simply a raw developer.
Darktable comes with cataloging features, in a fairly efficient and interoperable way, enough for my needs.
A significant differentiator to Rawtherapee, where this is still experimental and not in the main build, is Darktable's ability to do local/masked adjustments and support multiple instances of the same module.
When it comes to pixel shift images, wavelet-based processing and in general, sophisticated algorithms and color model support, Rawtherapee has an edge and i tend to go back to it for "difficult" cases.