I just joined like a gang, multiple number of groups. Some said Membership Required, some Public.?

Question

What is the Difference in membership?

Now one stated that the Moderator has to approved but otherwise they all seem the same registration status.

Answer 1

public means you can join without membership approval = you're a member right away

Membership requires approval means you'll remain pending until someone approves you

Answer 2

I don't know.  In my Y!gang the moderator had to approve me joining & it is sponsored by a few foundations.  I never go, I'm always here.

Answer 3

Membership Required means you have to be a member to access certain parts of the group.