#!/bin/bash
#Use find to list all the files in the directory then calculate the md5 hash for each file and pipe it sorted by filename to a file:

find /dir1/ -type f -exec md5sum {} + | sort -k 2 > dir1.txt

#Do the same procedure to the another directory:

find /dir2/ -type f -exec md5sum {} + | sort -k 2 > dir2.txt

#Then compare the result two files with diff:

diff -u dir1.txt dir2.txt

#Or as a single command using process substitution:

diff <(find /dir1/ -type f -exec md5sum {} + | sort -k 2) <(find /dir2/ -type f -exec md5sum {} + | sort -k 2