Both the listserve and the forums co-exist. You can use one or the other or both.
You are correct that the listserve is used via email whereas the forum is used via a web browser.
If you are still receiving emails from the listserv then you must be set up to continue using it. To post an email to the listserve you send it to
Vmug_members@vmug.bc.ca using the same email account to which you are receiving emails from the listserv.
Your observation that there are different discussions on the two facilities is correct. Some people prefer the listserv and only post there while others post to the forums and some will post a query to both at the same time to make sure it is seen by all.
One of the huge advantages of the forums is that you can post screenshots or other images there, whereas you can't post images on the listserv. This is very helpful when you are having a strange problem and want to show just what you are seeing (an error dialog box, a window of your settings for example.) It makes it much easier for someone trying to respond to your issue to know exactly what you are seeing.
Also you can be overrun with emails from the listserv, often about topics in which you might have no interest. The forums allow you to select ONLY the topics that are of interest at this time. And you can pick the time of day when you want to visit the forums, and not be distracted by a trickle of emails coming in at all times of the day.