The new feature provided by the Draw Explorer is the ability to group elements of your drawing together. Grouping draws these elements as one effective object. How this differs from elements drawn normally becomes apparent when you include cuts or erasings in your group.
You draw a tower, starting with a circle.
You then hollow it out using a circle cut and a line cut to make a doorway. The cuts show as red icons in the Draw Explorer and appear with red texture in the preview.
But you now want to give the tower a stone floor. So you draw a stone floor and move it to underneath the walls. Unfortunately, it disappears because the cuts affect everything below them!
But if you now select everything other than the stone floor and group them together, the cuts are limited to the group and the stone floor appears.
You can now do things like draw shadows, and position them easily to create the appropriate effect.