SAS Display Manager is a built in part of the SAS system. SAS/Studio is a separate process that is submitting code to a SAS session and retrieving the results and displaying them to your browser.
Since they are both using SAS to run the code you can pretty much do the same types of analyses.
The difference is how you interact with it and how much access you actually have to the SAS session you are using.
SAS Display Manager is much more responsive since it is part of the system. It is much more integrated, you can control your interaction using SAS code. You can make interactive windows using SAS code and the WINDOWS statement. And create your own interactive windows using SAS/AF and the SCL language. You can create command line macros to automate generating display manager commands.
You can run Display Manager on Windows and on Unix (using an X windows server to display the windows). But as you say they don't have a version that runs on MACOS (even though MACOS is a UNIX verison now).
At least with the installations I have seen it is much easier to run multiple SAS processes at once using DMS. But perhaps that is just a limitation imposed on use by the systems team that manages the SAS Servers processes needed to make the SAS/Studio interface work.
But with SAS/Studio is seems easier to me to manage editing multiple SAS programs at once within the same session. The "enchanced editor" that is only available in DMS running on Windows does help with allowing you to have multiple files open. But on Unix you would be forced to trying to use NOTEPAD windows instead if you wanted to edit multiple files at once in the same SAS session.
One of the things I miss with SAS/Studio editor (and the "enchanced editor") is the support for the line number commands. IN the regular DMS program editor you can type simple one or two letter commands in the line number area on the screen and copy/delete/replicate/reflow blocks of lines very easily. No needs to move your hands off the keyboard to pick up a mouse.
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