Anyone know what is included in the racket/base language. I am looking to compare the racket/base namespace definitions with the R7RS draft to get a first hand idea of how divergent Racket is from Scheme.
The difference is going to be huge, just like any other practical Scheme implementation. To give you a rough idea, I see more than 1300 identifiers from racket/base, and racket goes up to over 2000. Also, note that comparing the names is not going to be the whole story -- there are additional differences, like the fact that Racket uses immutable pairs by default, and like the fact that you get guaranteed left-to-right evaluation order.
A quick way to get the lists yourself for the former would be to make sure that XREPL is installed (have your ~/.racketrc file contain (require xrepl)), then start Racket with racket/base as the REPL language, and use the ,ap (apropos) command with no arguments so it shows you all of the bound names:
$ racket -I racket/base
Welcome to Racket v5.2.1.
-> ,ap
To read about the names, you can use the ,doc command, or just use the search box in the docs.