As a rule, published blueprints are upgraded as published blueprints.
However, there are exceptions to that rule. For example, vApp and vApp component blueprints are not upgraded, as vApps are not supported in the target vRealize Automation deployment. Multi-machine blueprints are upgraded as composite blueprints that contain blueprint components. Multi-machine blueprints that contain unsupported settings are upgraded as unpublished.
For related information see Upgrade and vApp Blueprints, vCloud Endpoints, and vCloud Reservations and Understanding How Multi-Machine Blueprints Are Upgraded.