Before release and version, we need to understand what build is – it is an executable or a library created by compiling source code. As new features get added, the older builds (or executables) no longer work – and a new release needs to be created for the general public to use.
This release is a version that was deemed acceptable to be used by a certain set of customers. There are plenty of other releases in the middle, where changes either cause undesired results or fail to work altogether.
Build number is the number of times the main program or library has been compiled: That’s why it makes sense to only release builds with meaningful changes. Version 3.1.4 means it’s the third edition with at least 1 major difference from 3.0, and 4 minor change events (bug fixes and/or updates).