What is the different between resource pools and workload groups in sql server?
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.