Sometimes the term "proofs" also means that the prints aren't completely adjusted to what the finished product would look like. That just depends from photographer to photographer. When I show my clients proofs from digital they are pretty much as the finished product will be. But when I show my clients proofs from medium or large format BW film, they are straight machine prints from the lab, or contact prints, and I will be doing more adjusting (tone, contrast, burn, dodge, etc...) in the darkroom when I go to make the gelatin silver prints.
I have also heard photogs refer to contact sheets as proofs, so possibly some people call index prints proofs?