These are two fascinating characters to compare because the elements listed—genre, sense of audience, tone, and vocabulary—have such a profound impact on how they portray themselves and how we come to understand them as characters.
The Wife of Bath's Prologue takes the form of a confessional—a popular form of literature in Chaucer's time in which the narrator confesses to their faults and announces an intention to live a better life from that point on.
Confessionals often quoted authorities like the Bible or various Greek thinkers. They typically had a somber tone and a serious, formal vocabulary. The narrator was typically quite aware that their audience would judge them poorly for their actions and sought patience and mercy from the audience as they spoke.
The Wife of Bath reveals her personality by using the confessional form but turning it on its head. She cites the Bible and Ptolemy to support her position, but her choice of Bible passages actually undermine her argument, and her quote from Ptolemy doesn't actually exist. Her tone is mocking and jolly throughout, with a coarse vocabulary full of sex puns. She doesn't seem to care much what other people think of her; she makes it clear that others' opinions will not have any effect on her behavior.
By Mary Rowlandson's time, the confessional had largely lost its popularity, but a related form—the tribulation narrative—had arisen. In these narratives, the narrator relates how they went through some type of ordeal. They recount specific events in a serious tone: While they might describe the narrator's emotions in the moment, the narrator tends to maintain some distance from those emotions, talking "about" them rather than displaying them. Their goal is to educate the audience and to offer themselves as an example of courage, fortitude, and faith in the face of adversity.
Mary Rowlandson reveals her personality by sticking to these qualities. She tells the story of how she was kidnapped by the Naragansett and lived among them for some time. She gives detailed accounts of specific scenes, and to demonstrate her courage and faith, she specifically describes moments in which she turned to the Bible or recited Scripture to herself or others for comfort.