Jerry pretty much covered it except for the fact that the deardorff has a larger tapered bellows allowing for lens board shift instead of having to move the standard up and down.

Which in my personal use would come in handy when using the back slitter feature w/ wide angle lenses for panoramic format.. One of few if not the only LF cam that will do those.. I believe the deardorff 4x5 special is also a 5x7" camera and I believe you can get a bag bellows to fit.

Given all that I suppose it's one of the most versitile wood field cams around