A group's type (open, members only, and so on) determines who can join, see content, participate, and invite new members.
Unlike spaces, which use permissions to determine access, social groups rely primarily on membership to determine access. Because groups do not exist inside spaces, they do not inherit any space permissions. Note that group owners and community managers can change the settings for a group after it is created.
Use the following tables to help you understand the different types of groups that can be created in the community. Most communities use the group scheme in the first table: if your community has enabled Group Membership Evolution, you'll see Public and Private as the main group types and should use the second table.
If you have Members Only and Secret Groups