Binaries are the machine executable files created by compiling source code.
The expectation on Unix machines is that the same source code works across all supported flavors, but it must be re-compiled for each machine. Packages for a particular Linux distribution are a counter-example. The expectation on Windows machines is that the same binaries work across all support flavors.
Therefore, much of the Unix gloss occurs during compilation and buildilng (scripts and pre-processor directives within source code), while on Windows, much of the platform gloss occurs at run-time (source code proper).