Differential Driver Maximum Output Voltage Swing
As opposed to single-ended signals that are ground-referenced, differential signals are self-referenced. This means that a differential signal made up of two single-ended lines that swing between 0 and +V can actually measure up to 2*V difference.

If we look at Figure 8 in your question, when the positive line is at 100V and the negative line is at 0, this is a difference of 100V (100V - 0V). When the positive line is at 0V and the negative line is at 100V, this is a difference of -100V (0V - 100V). This results in a total peak-to-peak voltage difference of 200V (100V - (-100V)).