In the Poisonous decision page, we see the characters presented as mice, however, this is the usual appearance in the book. The readers are used to view the people as animals but to think of them as real people. On this particular page, all of them have the same heads and they differ from each other by their clothes only.
On the contrary, the Prisoner on the hell planet page shows us the real human faces for the first time in the book. Due to the fact, that originally this page was not a part of Maus book and it was drawn independently long time before the creation of Maus, here the people are shown with their real appearances, not as animals. We can see people with mustaches, hair and real noses and lips. This contrast shows both the time gap between the comics and the fact that they are not a part of the same project. Additionally, this difference helps us to understand how the theme of tragedy is displayed differently by the same person but at different ages. In my opinion, the Prisoner on the hell planet page makes us perceive the scene as more recent and close to our present, rather than the Poisonous decision page, in which the fact that the situation happened long time ago can be felt by the readers because of its simplicity in clothes, backgrounds, and people in general.