There are 5 categories of rooms at any
DVC resort:
Un-declared inventory: These are rooms that haven't been sold to members yet. These really only exist in the actively-selling "new" resorts. These rooms are owned by Disney and they are available to cash guests only. These rooms aren't available to DVC members. The proceeds from these rooms go straight to Disney and don't benefit DVC members in any direct way.
Declared member inventory: These are the rooms that are available to be booked by members. A room must be declared before it's associated points can be sold. Disney can never sell more points than there are rooms to book. These rooms are only available to DVC members.
Breakage inventory: These are declared member inventory rooms that haven't been booked with 60 days or less to go. These rooms become available to cash guests, through disney. They are available to cash guests and DVC members. First person to book, gets it. The proceeds from these rooms are put in to the annual dues pot and helps reduce the dues for all members. It is a small number of rooms, and is usually a very small amount of money.
Time-share exchange inventory: These are declared member inventory rooms where a member exchanged it to stay at another time-share resort. These are the RCI or II exchanges. Other RCI or II members will book these rooms through the exchange company. These rooms are only available through the time share exchange company.
Non-time-share exchange inventory: These are declared member inventory rooms that were booked by Disney to pay for a member's non-time-share exchange. For example, if a DVC member uses points to book a
Disney Cruise, Disney will take those points and book rooms to rent out to cash guests in order to pay for that member's cruise. These rooms are only available to be booked through Disney for cash. You might be able to book them through member services, but only for member-discounted cash.
I hope this helps!