Compare two folders which has many files inside contents

To get summary of new/missing files, and which files differ:

diff -arq folder1 folder2

a treats all files as text, r recursively searched subdirectories, q reports 'briefly', only when files differ

diff -r will do this, telling you both if any files have been added or deleted, and what's changed in the files that have been modified.

I used

diff -rqyl folder1 folder2 --exclude=node_modules

in my nodejs apps.