If you upgrade via image - your are lost all configuration data (policies, ip-adress etc).
So more preferable for this situation (at my point of view) is to use updates.
As already mentioned there are only two ways for updating:
- "Update" e.g. MWG will download all necessary files from our download servers and installs them
- "Reimage" e.g. you re-install with an ISO/USB stock and import a backup
Usually if you restore a backup on the same machine the backup was taken from (UUID does not change) all configuration data will be migrated, such as IP configuration, etc. Of course all runtime data such as log files will be gone.
Thanks you Guys