Hi Carolina
It's not quite clear what you mean? One thing is schemas that are in the hive_metastore, the other is schemas that are in the Unity Catalog. But it is not the case that schemas are explicitly assigned to a cluster. This means that there are differences between schemas that are in the hive metastore and those that are in the Unity Catalog.
Differences between Unity Catalog and Hive Metastore are listed here:
https://docs.databricks.com/en/data-governance/unity-catalog/hive-metastore.html
In general, you can say that you should no longer work with Hive Metastore, but only with Unity Catalog.