These are both the same cmdlet,
Remove-Snapshot.
In the code you are using, you 'pipe' the snapshot object that you got with the Get-Snapshot cmdlet to the Remove-Snapshot cmdlet.
The cmdlet on the poster works in the same way.
The 2nd way of using the cmdlet is by giving the snapshot object via the -Snapshot parameter
Like this:
Remove-Snapshot -Snapshot (Get-VM DR_testsvr | Get-Snapshot) -Confirm:$false
