Yeah, I have always been a little unclear on that. I am more of a "work with what I got guy". I have an old school D1 and my coworkers have the D100. The D1 and 100 may be "photojournalism" Meaning that the design is well balanced, you can use the controls with your gloves, the capture rate is super fast and Nikon glass (in my opinion) makes up for in adequacies in file size. Plus they are really hard to break. Those little details are expensive.
Between you and I; the D1 stinks. The D100 is better, but that is not saying a lot. The D70 seems to be technological marvel. The camera is priced right and really popular. The best thing is to get your hands around the camera before you buy it. Then drop it and see if it still works. No one wants a camera that breaks if you drop it.