Compare two branches or commits on Github. Source: https://webapps.stackexchange.com/questions/62912/how-to-compare-releases-to-a-specific-branch/62974#62974
You can see the commits and changes between tags if you change the URL to the following format:
This will show you the count and changes of up to 250 commits made between the tags.
Similarly if you wanted to compare commits between branches the URL would be like this: