A wireless bridge forms a connection from AP to AP, and isn't a ratified standard, so implementations can vary.
There are three main types:
- Wireless Bridge - only packets between APs go over the air, so no wireless clients permitted to either AP, they must be wired
- Client Bridge - one AP acts as a wireless client to another AP. The "headend" AP is configured as a normal AP, and so permits connections from wireless clients. The Client AP is no longer an AP as the network card is used just like a network card in a laptop - for outgoing connection. However, the wireless connection is bridged to the lan ports, so you can have wired clients at the Client AP end.
- Repeater - this is the same as (2) except the Client AP retains its AP functionality and so you can have wireless clients.
It isn't always clear which of these are supported when something supports a wireless bridge due to the lack of standards. dd-wrt tries to support all three.