With the release of System Center 2012 Configuration Manager, Microsoft introduced the distribution point groups functionality. Distribution point groups provide a logical grouping of distribution points and collections for content distribution as described in the following Technet Article: Configuring Content Management in Configuration Manager, Create and Configure Distribution Point Groups
A Distribution Point can be made member of one or more Distribution Point Group, based on the content deployed to that Distribution Point Group and whether the Distribution Point is member of that group, the Distribution Point receives content which is defined for the Distribution Point group.
When distributing content you have the ability to choose whether you want to distribute to a either a Collection/Collections, Distribution Point or Distribution Point Groups. This is actually the point where things start to go wrong, since depending on who is performing the distribution of the content, different options are chosen.
My personal preference is to define distribution groups, and always distribute content to distribution groups. The main advantage of this is, that when you add a new distribution group in your hierarchy, you simply add the distribution point to the already existing distribution point group and it will be filled with the content defined …read more
Read more here:: Technical Blog of Kenneth van Surksum