DxDesigner is a schematic tool while HyperLynx 8.0 is a signal and power integrity design tool. In general, the HyperLynx family of products are for doing analysis of your circuits that you create in DxDesigner as well as analyzing your layout design (whichever layout program you use).
As far as differences between simulations, I'm not sure what you mean. Could you elaborate?
I think I figured out.