In Oracle® Database 2 Day + Real Application Clusters Guide 11g Release 2 (11.2), a policy-managed database is defined as:
A policy-managed database is created using a server pool. Oracle Clusterware allocates and reassigns capacity based on policies you define, enabling faster resource failover and dynamic capacity assignment.
In Oracle® Database 2 Day + Real Application Clusters Guide 11g Release 2 (11.2), an administrator-managed database is defined as:
An administrator-managed database is a database created on nodes that are not part of a server pool and are managed by the database or clusterware administrator.
In Oracle® Database 2 Day + Real Application Clusters Guide 11g Release 2 (11.2), the section About Oracle Grid Infrastructure and Oracle RAC, says that:
When you create an Oracle RAC database that is a policy-managed database, you specify the number of servers that are needed for the database, and a server pool is automatically created for the database. Oracle Clusterware populates the server pool with the servers it has available. If you do not use server pools, then you can create an administrator-managed database.