For GOS 6.0 and GOS 5.0 new patch levels are available:
https://www.greenbone.net/en/roadmap-lifecycle/
Greenbone OS 6.0.1 marks the availability of GOS 6 for all supported GSM types. This includes new orders as well as upgrades from GOS 5. For upgrades from GOS 5 to GOS 6, installing GOS 5.0.16 is a prerequisite.
In addition, both GOS versions comprise various improvements and bug fixes. Please refer to https://www.greenbone.net/en/roadmap-lifecycle/ for a full change log.
In total GOS 6.0.1 covers 27 improvements and GOS 5.0.16 covers 17 improvements.