Basically, the WDS devices can work as either a WDS relay or a WDS remote. The difference between the two is how they function — the WDS remote acts like an access point as to where wireless clients can connect to. The WDS remote is capable of communication with the base station and effectively passes information back and forth, the WDS relay is only an intermediary between these access points.
The primary purpose of the WDS relay is a range extender that allows WDS remotes to be well spaced farther from the base station. It is quite possible to have up to four WDS relays per base station and up to four WDS remotes per WDS relay. On a final note, the WDS is optimal if you want to cover a large open space or areas where the WDS relay can provide a line of sight to the main base station and the WDS remote.
The difference between the WDS Relay and the WDS remote is its function. The WDS remote is known to be like the access point because this is the area wherein the wireless clients can easily connect to. This will be in charge of passing the information to and from the area wherein it needs to send data.
The WDS relay will be the one in between the two access points that are available. The relay will also make it possible for different remotes to be connected to one port. They are both needed in the wireless distribution system but based on the details that are mentioned above, their functions are different from each other.