Dragon (supply), HTV and the Orbital (Cygnus?) use the Common Berthing Mechanism (CBM). It's a different method entirely from Shuttle's ODS or Progress/Soyuz capture. An CBM berthing port (not docking port) has to be powered up, once the ship is berthed, there is a bolting mechanism that torques down to something like ten tons (something like that anyway).
Smarter people here can have a better answer for you, but I'm pretty sure I've got the basic gist of it.
Wikipedia has some pretty good info regarding the space shuttle ODS, as well as APAS and CBM (and probe-and-drogue).