Download vs. upload site

What is the difference between the "Download Sites" and the sites which you upload your updates to?

I've built my updates and successfully uploaded them them to my ftp server (which requires a username.password) but I don't see how to use that same ftp server for downloading.

I've entered the same ftp server as a download site but there is no place to specify username/password and the check for updates fails with: (530) not logged in

What am I missing?

Thanks in advance

I've entered the same ftp server as a download site but there is no place to specify username/password and the check for updates fails with: (530) not logged in

You need to specify ftp download sites in the following form:

ftp://username:password@yoursite.com/path/to/updates/%file%