Traditionally texts are understood to have attempted to be singular in their approach to narrative. This might be understood as simply embodying a singular narrative line, or a single set of events that constitute the narrative of the text (and narrative here is being used in its broadest sense, as the linear and causal structure that all discourse requires).
However, because hypertext is digitally based it is able to be randomnly accessed, and so a strict form of linearity becomes unnecessary. In addition it becomes feasible to offer several narratives, several stories or versions, of whatever the text is about, and these versions may simply provide different ways of characterising the material, or could in fact offer contesting versions or opinions on, or around, the material.
For hypertext theory the point is very simple the effort in many forms of critical practice (and fiction) to embody these various possibilities has always been stymied by the linearity of the page, but can now be realised in this medium.