Contribution Vs Discussion Contribute to article means just that. If you are fact checking or adding details left out or sharing what you saw you know For example if someone posted the wrong time for a demo or forgot to add it or you went to the demo and saw something. Add comment to discussion is for sharing opinions or reactions to ideas in the post or debating what blogs were created for.
This is because a lot of people complain about the blog feel created by discussion and want more emphasis on first hand reporting. This is the compromise between the 2 camps. Also it used to be that comments with no contribution were hidden.
