"Fear. Fear is my ally."
Dark Jedi. Sith. The titles are often mistakenly using the titles interchangeably, especially with the release of the Prequels. This page and the Sith page hopefully will clarify the differences between the two Dark Side factions, and inform members of how they will be handled within Galaxy Force.
The Sith Lords are a more specialized and disciplined aspect of the Dark Brotherhood. The Sith are masters of energy and illusions, to the point where the illusions seem real in every detail: sight, sound, smell, and sometimes even touch. The Sith usually focus and channel their own power through ancient Sith artifacts, amulets, bracelets, armor, swords or other devices.
These artifacts often greatly amplify their power for an extended duration, yet slowly drain them over time. However, most Sith accept it as a sacrifice for their art. Naga Sadow, Freedon Nadd, Exar Kun, Ulic, and Kyp Durron are examples of Sith Lords and apprentices.
An excellent comparison/analogy of the main differences is relating them in terms of Dungeons & Dragons. The Dark Jedi are the classic Mages/Wizards dabbling in all the arts and powers of the arcane lore. They cannot cast/wield the most powerful spells of specialized disciplines, but are powerful in ALL areas. The Sith are the Specialists in illusions. The Illusionists excel in their craft and are more powerful than normal Mages within their own field, but sacrifice some power/knowledge of other areas for the sake of mastery within their craft.