What is the difference between the "-prescan" and "-showMissingItems" paramaters in the SyncTerminatedWorkflow operation for the NWAdmin command?

The parameter:

-Prescan, returns workflow instances that are not sync'd in the Nintex and Sharepoint history list

-ShowMissingItems, returns workflows where the list item is missing for a list workflow.

https://help.nintex.com/en-US/nintex2016/sp2016/NWAdmin/SyncTerminatedWorkflows.htm?tocpath=Administer%20%7CFarm%20administration%7CManage%20your%20farm%7CNWAdmin%20Guide%7COperations%7C_____41