There are like 20 of additional languages as part of the distribution. Some are variants, like "Typed Racket" that is like racket with static types. Other languages that are more/completely different and/or almost unused and keep for compatibility or as a demo of some strange feature. And also there are many user defined languages that can be downloaded as packages.
The batteries are included. I had to make a program that uses IMAP, SMTP and web scrapping. In another I used support for gzip and xml. In both cases, and all of that was installed by default. And also there are many user defined libraries that can be downloaded as packages.
Racket is more immutable than a normal Scheme. For example, lists ("cons") are immutable, and that allows the generation of faster code. Anyway, you can load a library to create mutable lists/cons if you need them.
There is more separation of the normal code from the code in macros. So normal code does not affect the code inside macros. Some people like that, and some people dislike that. It's better to reason about macro expansions, but to share a function between normal code and a macro you must define it in another file.
It's quite fast in the Scheme family https://ecraven.github.io/r7rs-benchmarks/ Still like 5x slower than C, but 5x faster than vanilla Python. https://benchmarksgame-team.pages.debian.net/benchmarksgame/... YMMV