Salt water and fresh water are quite different, and few creatures can survive in both; my mind can be either be "Salt water" or "Fresh water", but not both at the same time; "new jazz" is fresh water, and "Old Jazz" or Jazz Jazz, is Salt water.
"I think", that abstract jazz, would be a better term for "new jazz"; that's judging from the two that Acman posted. "Old and New", are far to ambiguous, but here again, we have to call it something. As long as we know what we're talking about, no one will get fined for wrongful terminology.