My understanding that for the Sith, Lord and Darth are one and the same, with the latter being a contraction of the formal "Dark Lord of the Sith."
Of course, I've been wrong before.....
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[-=Nazgul Squadron=-]
[-=Phoenix Wing=-]
FM/SCRW Delia "Evil Clown" Cael/Nazgul 3-2/Phoenix Wing/mSSD Atrus/1VENF/VEN/VE/(=*A*=)[SoA]
"So tell the judge I'm ready for the vases.
I'll dance in their faces when the guitar sounds.
Won't be long, I won't be gone.
Been leaning towards the shadows all along.