Release Terminology (Patreon)

Pre-Alpha refers to a game releases that are not feature-complete. Here we are usually still deciding on what features the software should have. 

This is the earliest stage of game development.

Alpha refers to early game releases which are stable enough for limited testing. 

Alpha builds are usually not feature complete. 

Beta refers to more polished game releases that contain most of the major features in its early iterations. 

This is the final major stage of testing.

Release is the final product ready to be released to the public. The final release is typically chosen by the developers from a set of release candidates that are built after the beta stage.