He broke it down into Tiers.
Tiers would be the entire Xenforo.com/community site where you see all the forums
Tier 2 would be the categories(I.e.Public Forums, Xenforo Bug Reports, etc etc
Tier 3 would be the individual forums(Pre-Sale Questions, General Feedback)
When you click Tier 2 to ONLY see the Forums that are apart of the category Public Forums it doesn't redirect to a new page to show you only the forums attached to the Public Forums category.
It just simply moves the page up to the link you clicked.
ON Ipboard, if you click "Public Forums" it'll take you to a new page that shows you ONLY the five forums that are attached to that category and from there you can simply click which of the forums you want to go into.
I am glad i noticed this before buying because this could be a problem...is that something that could be fixed?
Here's an example of what i mean when i said it redirects it to it's own page to show the individual subforums
^notice how clicking the category takes you to a page that shows it's attached forum?