The Discovery History shows you all the Tasks which ran on your Inventory Analyzer. Here you can see which Data Source the tasks used (Discovered In), if new Assets were found or existing ones were updated, and the status of the Task. You can also see which Template was used and the NMAP Arguments of the your NMAP Task.
To see the New Assets from a Task, click on the number
New Assets Count Column.
To see the Updates Assets from a Task, click on the number
Updates Assets Count Column. You can see which
Rule triggered the Update.