Persuasive speaking is a type of speaking that includes motives and supportive evidence. This is very important, as the main purpose of persuasive speaking is to convince the audience of a particular position. It is a lot more likely for the audience to be convinced if the speaker includes the motives for his position and the supportive evidence he is providing.
The difference is that mrs. Whitlaw thinks dragons are scary and freaky but Moon Shadow is the opposite, after he tells all the stories about dragons she changed her mind