Not at all, Darth is from Dark Lord of the Sith, so it's a Sith title. A dark jedi master is something completely different than a sith, it's more like an evil jedi eg. Assajj is a dark jedi, Dooku is a Sith Lord=darth Tyranus.
Darth isnt a Sith title and was misused in KotOR 1,
Darth is a dark jedi title,
Sith get their own titles
And your confused between the Sith Empire and the Galactic Empire
And since Tyranus was the emporers lacky he was not a Sith
The emporer and "DARTH" Vader were not Sith, as they did not follow any of the rules and merely wanted to control the galaxy by wiping out all force sensitives, not just jedi, whereas a sith regime would of spared jedi which fell to the dark side
So then give an example of a real sith.