First class versus normal class

Hi,
It seems I cannot locate the differences between first class and normal class pass on their website. I found it once before but maybe they updated it and forgot to add it?
Anywho, does anyone know the differences? I would like to use the Shinkasen but I know that the normal class doesn't have a "walk on through" ability, or at least since I last looked a few months ago.
Thank you, your help is greatly appreciated!