Hello Frank,

The difference between with Q&A & without Q&A is you can mark whether the question is answered or resolved.

If Q&A is enabled the as shown in this screenshot http://screencast.com/t/SbxCeCOL2 the moderator menu on the right hand side will display mark resolve as shown in this screen shot http://screencast.com/t/BG0itkEcBW when is clicked it will mark the discussion or Q&A session as resolved as shown in this screenshot http://screencast.com/t/ATZJYX7os9.

But if the Q&A is disabled as shown in this screenshot http://screencast.com/t/6SufQnUIt the mark resolve button did not turn up in the moderator menu as shown in this screens shot http://screencast.com/t/DTg6ysHGMeH . It is mainly for general discussion.

Hope this answers your question

Regards
Kheng Wei