Mattermost ships with a new version on the 16th of each month in binary form.
The feature releases have new features added.
Extended Support Release (ESR)
Extended Support Releases are releases that are maintained for a longer period of time. They will receive backports for security fixes and major bug fixes for the length of their life cycle. Read more about Extended Support Releases here.
Major releases are planned once a year for June. Major releases follow a theme and include multiple new features.