"The Cold Equations" contrasts life on earth with life in the space frontier. In what important ways are those settings different?

The central difference, which of course relates to the
title of this chilling short story, is that life in the space frontier is much harsher
and crueller than life on earth. Note how the narrator tells us, as Barton contemplates
the way he must eject his stowaway into space to face a certain death, that this was the
"law" and there was no "appeal":

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It was a law not of men's choosing but made
imperative by the circumstances of the space
frontier.

The narrator goes
on to explain how fuel is measured out exactly and even a slight addition in the weight
of space shuttles would result in their destruction:

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The stowaway had signed his own death warrant
when he concealed himself on the ship; he could not be permittted to take seven others
with him.

Such "cold
equations" rule the space frontier, causing Barton, even though he would love to be able
to save the life of Marilyn, to actually have to be the agent of her death. The
realities of life in the space frontier call for such hard and unyielding rules that
result in such difficult consequences for people such as Marilyn. This is the biggest
central difference between life on earth and life in space.