Oops, my bad. I got mixed up and said the wrong thing to you in my first reply.

"This collection is anonymous" means that author names will appear as "Anonymous", and "This collection is unrevealed" means that none of the fanworks in the collection will be shown at all, instead there will be a placeholder saying "Mystery work".

I'm sorry, it's pretty confusing for me too, even though I have actually moderated collections before.