I don't have facebook so I'm just going by browsing facebook, but it seems messageboards are a lot better for debate and discussion. Facebook is more of what you may text someone or thinking you are so important that everyone wants to know what you are eating for dinner, where you are eating. what time you got up or a bunch of other stuff.
just my opinion by looking around.
Messageboards you seem to have more meaniful discussions and debates. more in depth stuff