ksh compare two files

In a directory I have four files named something like this
source_client002.out
dest_client002.out
source_client002_data.out
dest_client002_data.out.

I want to compare the source_client002.out with dest_client002.out and source_client002_data.out with dest_client002_data.out and generate a report with the differences using shell script. Please advise. There are more files in the directory with different client numbers where I need to similarly compare.