Well I hate to piss on anyone but having used photopost for a couple of years and now vba on both of my forums the difference to me is
PP has almost daily updates with poor documentation and for a novice every update is like a nightmare. The styles don't match well and you can count on that email from that new member that has never logged out to tell you that he can't view images.
VBA while not having as many options was a breeze to install, no double admin panel. The styles look perfect, data base integration was perfect and no cookie issues like new members always have with PP. I have only been using VBA a couple of weeks but couldn't feature going back. If anyone is interested I have a copy of PP I wish I could sell.