is the act of arranging elements that obeys a certain set of rules or specifications
Ordering is the act of arranging elements that obeys a certain set of rules or specifications. These rules may affect the way a search result is presented, or more accurately, in what order the search result is presented. The same goes for navigation links in per example global navigation; which link is ordered first.
Questions having the orderning tag regards the act of ordering certain elements in a particular way that affect User Experience.