The most significant difference between Earth and Venus (and the difference that ultimately defines life on Venus) is that Venus has a climate of perpetual rainfall. It rains continuously to such a degree that, as this story opens, the children in the classroom are excited by the knowledge that, for just one brief moment, the sun will be visible in the sky. This is an event so rare that, in a class of nine years old, none of the children save Margot herself (who had actually been from Earth) has any memory of what the sun actually looks like. The transition of living on this world of perpetual rainfall seems to be at the center of Margot's difficulties adjusting to life on Venus.

A second difference lies in humanity's adaptation to Venus's harsh environment. On Earth, one imagines that life is still lived outside. At the very least, the story certainly suggests that this is the case, given that Margot has memories of the sun and sky. On Venus, however, life has taken a very different turn. The act of colonizing such an inhospitable world has forced the humans to live underground. The children are described playing "in the echoing tunnels of the underground city" (Bradbury, "All Summer in a Day"). This detail paints a very different picture of life on Venus compared to Earth.