Hi,
Test Recovery helps you to test the replica that you have at the recovery site without impacting the ongoing replication. That is after you run Test Recovery, you have a running VM on the recovery side and still replication traffic is ongoing from protected to recovery site. After you verify that your Test VM is OK, you can perform Clean up which will remove the VM and return the plan to Ready state.
Planned Migration mode implies that your both sites are up and running. When planned migration is executed, it will perform synchronization and then will stop the source VMs as part of the process. If any of these fails, the whole plan will fail and you would need to fix things and re-run the plan again.
Unplanned Failover (Disaster Recovery) implies that some unplanned event has happened with the source site and it is unavailable. Then after executing the plan you will have your VMs recovered on the recovery site and continue working. When the site that has gone is back and up and running again, you can perform reprotect/failback to reverse the replication direction and start using your original site as primary site again.
Hope this helps.