What is the different between resource pools and workload groups in sql server? In SQL server one can use resource pools and workload groups, what is the difference between them? Why should I use one over the other?
Resource Governor Concepts


  
  Resource pools. A resource pool, represents the physical resources of the server. You can think of a pool as a virtual SQL
  Server instance inside of a SQL Server instance. 
  Workload groups. A workload group serves as a container for session requests that have similar classification criteria. A workload
  allows for aggregate monitoring of the sessions, and defines policies
  for the sessions. Each workload group is in a resource pool.