raspberry pi noobs buildroot overlay
The raspberry pi noobs repository is based on buildroot. In Commit f7e730a it got updated to buildroot commit 083f853.
This repository contains the changes between the base buildroot version and the one used by noobs.
Extract the original buildroot next to the version in the noobs repository. Then remove all identical files with fdupes:
fdupes -rdN ./buildroot ./buildroot-083f853
Now you have a big pile of empty folders. Delete them with
cd buildroot
find . -type d -empty -exec rmdir {} \;
Now you can look at a diff between the versions:
diff -r ./buildroot ./buildroot-083f853 | grep -v "Only in buildroot-083"