I baked one and put it on a 6" cake board. It was small and I wound up cutting over an inch off the board.. The outside base is 4&3/4", inside base is 4&1/2". It tapers up to 6". This is the Wilton pan. I don't have the other pan to compare. HTH
I think it would look better on an 8" cake since the top of the cupcake is almost 6" it would be the same size as the 6" cake that it's sitting on.