The difference between The Dark Knight and Dante? Well, for starters, one is Vergil and the other is Dante. XD The dif. between The Dark Knight and Dante is the same dif. between Vergil and Dante.
Vergil is known for incredible speed while Dante seems to have more brute strenght. Although sometimes I think Dante can be just as fast as well as Vergil being just as strong. But anyways, that is what they're known for.
I believe Vergil was given the name LDK because he a son of Sparda, and we all know Sparda was the original LDK, so, being next in line, it is only natural that Vergil gets such a title while living in hell. Heck, in a way, Dante can also be classified as a LDK. Although he's not dark, hmmmmm maybe he can be called the Legendark Light Knight. ^^ Cuz Vergil is labled the Dark twin, so I guess Dante is the Light twin.
...I'll shut up now.