The difference will be huge, like any other practical implementation of the Scheme. To give you a rough idea, I see more than 1300 identifiers from racket/base, and racketup to 2000. Also note that comparison of names will not be the whole story - there are additional differences, like the fact that Racket uses immutable pairs by default, and, as a fact that you get a guaranteed order from left to right.
, , XREPL ( ~/.racketrc (require xrepl)), Racket racket/base REPL ,ap (apropos) ,
$ racket -I racket/base
Welcome to Racket v5.2.1.
-> ,ap
, ,doc .