In Community, you'll notice that there are two separate sections - Members and Users. Each of those sections serves a different purpose:
A Member is an entity that holds all memberships, billing information, and bookings. Members belong to the Admin Portal.
A User is the entity that links to the Member and holds the permissions necessary to use the Members Portal (more about that in this article). Under Community, the number next to Users shows how many members have access to the members portal.
You can see the different permissions that are being granted to Users depending on their Status in the system here.