svn diff lists all differences two files or a set of files

$ svn diff file1 file2

-r option shows difference between two versions of a files or set of files

$ svn diff -r5:10 some_directory

This code shows all changes made to the directory and all its contents between version 5 and version 10

$ svn diff --summarize some_directory

This code only lists files which have changes, not the details of what has changed inside them.