Get insight into what has changed between Magento releases.
See changelog for 2.3 release line.
See changelog for 2.4 release line.
# Make sure you have all branches and tags present.
git fetch --all --tags
# Diff Magento_Catalog frontend templates between 2.3.5-p2 and 2.3.6
git diff 2.3.5-p2 2.3.6 Magento/module-catalog/view/frontend/templates/
# Diff JS changes between 2.4.0 and 2.4.1
git diff 2.4.0 2.4.1 Magento/*.js
Adding a new release is quite simple, run the following:
git checkout 2.x
./update.sh 2.x.x
git add Magento
git commit -m "Add Magento 2.x.x"
Although Magento Open Source is, well, open source, the release process is not as open source as one would think. The release process happens at Magento HQ and the only outcome we (the community) get is a release tag in the Magento repository with thousands of commits between the new and previous tag.
In the olden Magento 1 days, it was possible to see what had changed in an update. That was due to the fact that all the vendor code was being checked in to Git. There were also community initiatives like OpenMage/magento-mirror to make the changes available on Github.