Query List action is used to fetch the items meeting the required filter criteria and then do some action on those items. For example, we can fetch tasks that are ‘Open’ and are of a particular ‘Type’ and then send a reminder mail to assignee of each task. The filter conditions are specified in the Custom Action settings and cannot be changed during execution. More details on this action are here: Query List action configuration
‘Query list (Search)’ action allows user to specify the search text and select the required items when custom action is executed. User selected items can then be processed in subsequent actions like normal Query List action.
Query List ( Search) action in designer custom action
Grid Settings Tab:
Variable Mapping Tab:
For more details refer below article
Query List (Search) action configuration in Custom Action