system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] what's the difference between a Sith and a Dark Jedi?
gpt
All sith are dark jedi, but not all dark jedi are sith. Eloquently summed up in the novel *Darth Bane: Dynasty of Evil* by Jedi Master Obba;

> "What's the difference between a Sith and a Dark Jedi?" Lucia asked.

> The Ithorian stopped pacing and turned to face them, instinctively addressing his audience like a teacher giving a lesson.

> "The Sith were the sworn enemies of the Jedi and the Republic. They sought to wipe us from existence; they sought to rule the galaxy. They united their strength in the Brotherhood of Darkness, drawing countless followers to their cause with false promises. They amassed an army of individuals foolish and desperate enough to believe their lies, and they plunge the galaxy into a war that threatened to destroy us all."

...

> "A Dark Jedi, on the other hand, has much smaller ambitions. He - or she - thinks only of himself. He acts alone. The ultimate goal is not galactic conquest, but personal wealth and importance. Like a common thug or criminal, he revels in cruelty and selfishness. He preys upon the weak and vulnerable, spreading misery and suffering wherever he goes."

The Sith, therefore, have had many differing incarnations (the ancient Sith order of Marka Ragnos/Naga Sadow, the Rule of Two, Brotherhood of Darkness, Rule of one) but are all unified by vastly similar secrets, rituals and end goal of galactic domination. It is very much a club that not just any Darkside user can join but must be inducted by a member into.

Non-Sith dark jedi tend to be out for their own non sith goals, unless they are part of a group of Dark Jedi under the control of the Sith (not inducted into the Sith order but generally following the Sith in order to take the eventual chance).

The Sith also believe themselves to be inherently superior to all non-sith dark jedi - The Sith use their emotions, but can also control them and not let themselves be slaves to them. Furthermore, at least according to Count Dooku in his first encounter with Asajj Ventress, the Sith don't allow themselves to feel any fear, which although leads to the dark side does not provide much use and is a liability for a Sith Master.