When you manage production, you typically want to keep track of build history. This normally includes information about how many units of a project/BOM were built, the build date/time, and possibly some comments. While this is enough for simple production, it doesn't cover the needs of more complex builds.
In practical scenarios, each build has its configuration. This includes additional information such as:
In PartsBox, this information is entered using the project build screen.
All of this information is now stored alongside the build history, so that you can go back anytime and check how a particular build was configured.
This lets you control your production even better, and have a historical record of every production run configuration. It's a required feature of any MRP (Manufacturing Resource Planning) system.
Build Configuration History is a feature available in all the paid plans, but not in the free Hobbyist/Maker plan.