why

do software packages come with multiple executable binaries? I tried reading my SICP but it doesn't seem to be in there.

Are some lines of execution so specific to one obscure condition that it's almost never used and they take it out of the main process image to make it smaller.?

x86-32 vs x86-64 comes to mind

In the windows world there's also .zip, .msi, .exe installer, and so on.