Thread:"public" "private" "open groups" "closed groups" (1)

I think the distinction between "public" and "private" may not be clear, e.g. how does this concept of oppositions link to "open groups" vs. "closed groups"? Does a "public" approach imply that the people who work on something show this to anyone else immediately AND anyone can join in as they please? Or is there no interrelation between those two sets of concepts in our context? If there is not, why not? ;-)