Bogwood and driftwood whilst outwardly the same are 2 different thing as the conditions that created them are completely different
Bogwood is created in Peat bogs where the composition of the wood is aftected by imersion in Peat and acidic compunds
http://en.wikipedia.org/wiki/Bog_oak
Driftwood is wood that has drifted either in salt or freshwater for a considerable period of time and has had a completely different set of organisms work on its conversion,
http://en.wikipedia.org/wiki/Driftwood
Bogwood is more likely to lower the PH of a tank than driftwood will.