Running worst case corners from ADEXL

Hello,

I am trying to verify my design against PVT by running the worst case corners. I have found that I can define my corners in two methods in ADEXL:

1. From Single Run, Sweep and Corners : I can define my corners and run the simulation

2. From  Creat Worst Case Corners

What are the difference in between? and which one should be the best.

I am using Cadence Virtuoso IC6.1.5

Thank you