Racket is kind of its own ecosystem. Guile is much more intended to integrate well with a POSIX-like environment, and the GNU system in particular. I've used it for 25 years or so as a scripting language, where other people might've used Perl or Python.
It's also more easily embeddable than Racket. Many GNU programs, including GNU Make, gdb, and GNU TeXmacs, are scriptable with an embedded Guile runtime.