I noticed that everyone is Making a Comment vs Starting a Discussion. I mention this because they are different and it is very helpful to understand the difference and how it will effect your group.
Comments
Roll off when new comments are posted, there is only so much room reserved for comments
You cant not directly reply to someone who has posted a comment
If multiple people make comments about different subjects you cant really follow the discussion
Discussions
Are listed by most popular, meaning if you reply to a comment it rises to the top of the list of discussions.
There is an alert feature called Follow that sends you an email when someone replies to a discussion that you are interested in. So if you start a discussion and weeks later someone replies to you, you will know.
Discussions are contained and grouped together so you dont have to read topics outside the discussion to find replies to your issue or question.
Discussion can be tagged so that you can Search for them by topic.
See the Grooming or Owner Recommended Breeder's groups to see examples of what I mean.