How can I diff a directory for only files of a specific type?

I have a question about the diff command
if I want a recursive directory diff but only for a specific file type, how to do that?


I tried using the exclude option but can only use one pattern only:
diff /destination/dir/1 /destination/dir/2 -r -x *.xml



with the command I can only exclude xml file type, even though there are files in the folder image type (png, gif, jpg), txt, php, etc.


How can I diff only certain file types?