Switchover and Failover have a lot in common. Both involve moving the resources to the Standby and both make the Standby the new Primary. However, one distinction is the fact that Switchover is Planned and the standby is maintained, where the failover is in nutshell “ditching” the primary, it gives up on the primary and moves directly to the standby which will become the new Primary.

To summaries:

• Switchver:
  • Planned
  • Maintain the “Primary - Standby” relation
  • Moves sessions and services
  • No or very little downtime for the client

• Failover:
  • Unplanned
  • “Ditches”/“Abandons” the primary for the standby (New Primary)
  • Doesn't transfer sessions/services
  • Depends on the configuration, but some downtime.