The Originals technically had it's season premiere pilot during this past season of The Vampire Diaries, by way of a back-door pilot. However, since the new spin-off series was officially picked up for next season by the CW, they have now decided to give The Originals an independent premiere of it's own to be shot this Summer.
What will fans see in this new premiere?
Chronologically, the new "Originals" premiere will follow the backdoor pilot. That episode -- and everything that happened in it -- will still exist in the show's universe. The purpose of the new premiere is instead to move the story forward and to introduce the characters and concepts to new viewers who may not have watched "The Vampire Diaries" in the past.
There will also be a new character, Davina. Played by Danielle Campbell, this character is a witch in New Orleans who gets tied up in Klaus' (Joseph Morgan) return to town. Davina was originally supposed to be in the backdoor pilot, but the part was cut during editing.
It's important to note that this new premiere is not supposed to replace the already-aired pilot in any way. All of the big events -- Klaus' return to New Orleans, his conflict with Marcel (Charles Michael Davis) and the reveal that Hayley (Phoebe Tonkin) is pregnant with Klaus' child -- will remain part of the show's chronology.