The first is a drag and drop style method. The user has to grab the specific component from a list of components and place it on the page. This is nice because it allows them to place the module where they want, but the user has to click and drag to achieve this effect.
The other method is a click to add method. The user clicks on the component they wish to add in the list and it adds the module to the page at the top most level. This is a good approach as well, but the user then has to go over and re-position it (if they choose to do so). I could also see this getting confusing if the user has lots of modules added in different locations, they might not be able to see where it was placed.
Is there a best practice on how users should add components to a webpage? Do users prefer to drag and drop or click to add? Are there any statistics on this?