This setting specifies the default destination for comments on articles in a particular space. The default is for comments to target the same space as the article or comment being commented on, but if you want to encourage users to post comments to a different space, you can select an alternative "moderation space."
When posting a comment, users who have Comment permission in the moderation space will see that space is selected for them by default.
Generally, the value of using a moderation space for comments is that it allows a different set of permissions to be applied to comments from those applied to articles. For example, a different set of users can be granted Read Drafts and Publish permissions in the moderation space, allowing a different set of moderators to read and approve or reject draft comments.
