One of the things most PostgreSQL replication solutions have in common is that they have a single master node. Bucardo is instead a multi-master replication solution, also implemented with triggers; refer to http://bucardo.org/.
Anytime you have more than one master, this introduces a new form of replication problems. What do you do if more than one node modifies the same record? Solving that is called conflict resolution in replication terminology. Bucardo provides a hook for your application to figure out what to do in that case, after it does the heavy lifting work on the main replication chore.
Bucardo is also very asynchronous. Instead of expecting that nodes are in constant contact with one another as most database replication ...
