Mozilla thunder bird ESR releases

Mozilla releases a Thunderbird Stable and ESR version every six weeks just like it does for the Firefox web browser. While that makes sense for actively developed products that get new feature additions regularly, it does not really make a difference in regards to the Thunderbird email client anymore as it does not really receive new features regularly anymore.
The difference between stable and ESR releases is that Extended Support Releases are more restricted in regards to updates they receive. While they do get all the security fixes and such, major changes to the program's core are not added directly to them.
These changes are only rolled out every eight release cycles equaling every 54 weeks. The idea behind this is to give Enterprise and business users enought time to adapt to the changes before they are rolled out.
Thunderbird development on the other hand has been put on hold more or less, which means that the stable and ESR versions have been identical in the recent past.