This may not serve to show anything more than I am a lousy photographer.
I was using my cell phone, and the stainless tubes really didn't react well with the flash...but I think they will serve the purpose.
In any case, I bought a SW9VE 16-round magazine for my SD9VE, since I couldn't find the SD magazines anywhere. I called S&W, and they are sending me an SD base plate for it.
As far as I can tell, from an external examination, there is no difference in the two magazines other than the base plate. The tubes look exactly the same, except for one small difference: on the front of the SD magazine (and I checked both of the SD magazines that came with the pistol) there is a rectangular depression right at the top of the tube; on the SW magazine, there is the same depression, but it isn't as well defined. (SD mag is on the left.)
Otherwise, the followers appear the same, and the tubes appear the same, and the SW magazine goes into the SD easily, locks in easily, and locks open the slide. Even the SW base plate doesn't look too bad with the SD frame.
I didn't take the magazines apart to check the springs and internals, but I will when I get the new base plate. However, but magazines have the same colored spring, if that means anything.