What's the difference between Saveas an edrawing  file and Publish an edrawing file?

What are the benefits of each?

I have been using publish but I see some differences when I saveas.

When I publish, edrawings will launch with the file but the publish location directory will be

whatever dir I was in last.  I have to navigate to the correct dir and save.

When I saveas, edrawings does not launch but it saves to the correct dir.

Also, when I saveas, the file extension .EDRW is in all caps.

When I publish, the file extension .edrw is all lower case.

Thanks