In my mind, the “Historical Notes” section of The Handmaid’s Tale was used primarily to further some of the points that come up time and time again throughout the novel. The main point that she really wants to hammer home is her idea that the state of constant oppression which these people live under cannot be broken unless there are more brave souls who are willing to rebel and risk their lives to put an end to the horrible way in which they all are currently living. She uses Offred as her example throughout the story, and most notably here.
Atwood further depicts Offred’s devotion and dedication to ridding their society of the horrible oppression they face by simply showing her rebellion. In the story, Offred does not have any idea what might come over her actions. She waits for the truck to take her away. She has zero knowledge as to whether or not she will be persecuted for her actions, a sad reality that speaks to the inability to stand out or speak out against Gilead. She contrasts this with her epilogue, where she shows how Offred’s actions have actually bettered the society substantially. She remakes the maps, and immediately shifts back to a society that places emphasis on learning, but even moreover on individuality.
It is clear that Atwood attempts to show the contrast between the two endings in order to show the differences between what life is really like for them, where they have to be concerned about acting against the slightest of rebellions, and a properly run society in which changes are made for the better of the people.