Nightly Build:

The nightly builds are automatically built each night from the current codebase for that product, which contains code changes (i.e. bug fixes) from throughout the day. If the build is successful it is made available, otherwise it is not made available. This process is mostly automated. Nightly Builds are only available to Gold and Silver members of the 4D Partner Program.

Hotfix:

Every once in awhile (usually after an important bug fix), we will take a particular nightly build as a candidate and run additional tests on it; these tests can take multiple days to complete. If all of the tests are successful the nightly build gets the label of Hotfix and is made available as such. Hotfixes are only available to Gold and Silver members of the 4D Partner Program.

Final Release:

The final release goes through a similar process as the one i described for the hotfix, except for that the number of tests ran on the final release are much more which include manual tests conducted by humans. These tests can take up to multiple weeks to complete. Final Releases are available to the public.