Who can tell the difference between the two options

zhoubing2525

Hello everybody, this topic is about the command of 'wrap surface' in GSD(general shape design).
To begin talking about it, let's look at the two pictures below,  which show the diagrams of how to create wrapping surface. As you can see in these pictures, there are two options for you to select to make a wrapping surface. One is '3D', the other is 'Normal'.  I am quite confused about these two diagrams. To make matters worse, there is nothing in the reference book to describe the defference between '3D' and 'Normal'. Is there any one who can help me? I am looking forward to your ansawer. Thanks...

龙游九天