Big difference. Simply put, one is a consumer camera, and the other is a professional camera. Pushing the limits of my D700, I get photos you can't get on the D90. In the hands of a top pro photographer, they could get better photos on the D90 than those taken by an amature on a D700. Compare and understand the differences, and decide if it's worth the price for you. I love my D700. Had a D70s, D80, and D300 before this one.