Using the conversion rules in Libraries and Collections, and R6RS library can refer to modules that are implemented in other dialects supported by Racket, and other Racket modules can refer to libraries that are implemented in R6RS.
Beware that a pair in R6RS corresponds to a mutable pair in racket/base. Otherwise, R6RS libraries and racket/base share the same datatype for numbers, characters, strings, bytevectors (a.k.a. byte strings), vectors, and so on. Hash tables are different. Input and output ports from racket/base can be used directly as binary ports with R6RS libraries, and all R6RS ports can be used as ports in racket/base programs, but only textual ports created via R6RS libraries can be used by other R6RS operations that expect textual ports.