WinSCP GUI Download vs Command Line GET

BACKGROUND:
I am trying to download a file from a trading partner's WS FTP Pro server via SFTP. If the file has been successfully downloaded, the file on the server will be renamed to include the timestamp and moved from its current directory to another one (i.e. /backup).

PROBLEM:
When downloading using WinSCP GUI client via drag+drop, file is successfully downloaded AND the server is able to do its normal operation on the file.

When I download using command-line script, the file can be successfully downloaded BUT the server is not able to move the file from current directory to /backup, just renamed with a timestamp.

QUESTION:
What is the difference between WinSCP GUI download vs command line GET?
Is WinSCP GUI download performing a special kind of "GET"?
How can I replicate the intended effect of the GUI download on the FTP server using the command line?

Thanks for your opinion and support!

So the server detects that the file was downloaded and move/renames the file automatically?

Please attach full log files showing download using GUI and the script (using the latest version of WinSCP).