To me, the difference is in the level of trust you place in the information you get from a forum. With anonymous postings here, everything needs to be taken with a serious pinch of salt.
On the LAA forum, you can verify who said what, and can trust that information to a much greater extent. People are accountable for what they say.
Other advantages, as others have said include because it isn't anonymous, it can be moderated with a very light touch. You just don't get trolls. There are pretty much no trolls who allow their real name to appear. This means that resources at the LAA can be kept in the things they do best.
The other thing is that this can only be changed after a resolution from the National Council. To get this changed, you will need agreement at the top level.
Now if only I had something interesting to contribute to the LAA forums I might register... (and I don't have my LAA number on me at the moment which doesn't help!)