Does pt-table-checksum point out rows that are different between Master and Slave?
By default, pt-table-checksum displays as result all tables even if there is no error or diffs.

If you want to display just errors and diffs you can add the --quiet to the invocation of pt-table-checksum


  Print only the most important information (disables --progress). Specifying this option once causes the tool to print only errors, warnings, and tables that have checksum differences.
  Specifying this option twice causes the tool to print only errors. In this case, you can use the tool’s exit status to determine if there were any warnings or checksum differences.