Analytics lets you create a view in which you apply filters to rename URLs. Since this approach permanently replaces the URL data in that view, you can only see your data in the altered format, and you cannot drill in to the individual pages from the group view.
An additional limitation to this approach results from the grouping methodology. Often the URL construction by itself is not enough to identify the conceptual group to which you want to assign content. For example, some content-management systems display all URLs in a virtually identical manner, differing only in the content ID numbers. In these cases, the URLs are so similar that even a filtered view can’t group them effectively. Under these circumstances, you want to assign content via the tracking code.
If you have previously used filtered views to simulate Content Groups, consider setting up the new Content-Grouping feature instead. Once you have enabled Content Grouping, create an alternate view for your data that does not have the old grouping filters applied. You might want to keep your old filtered view for historical comparison.
It is possible to include content in multiple groups with any of the three methods. However, when you use the tracking code, you can include content in only five groups (index numbers 1-5); and if you make a call to the same index number again in a subsequent hit, then that later call takes precedence.