The original text of the New Testament has not survived in any manuscript. All manuscripts contain variants that developed during the textual history in the process of continuous copying.
The initial text of the tradition is the text that precedes this process of copying. Since it has not survived in any manuscript it has to be reconstructed on the one hand on the basis of surviving text witnesses and the overall picture of the textual history resulting from it and on the other hand by virtue of all that is known about the intention of the author. This leads to a hypothesis about the initial text.
Between the text of the author and the initial text there may be developments that have left no traces in any of the surviving manuscripts. Thus the initial text of the tradition is not necessarily identical to the text of the author. However, as along as no substantial reasons argue against it, it is the simplest working hypothesis that the initial text corresponds largely to the text of the author, apart from small variants that are to be reckoned with during the act of copying.