I think the simplest answer is that it's often essentially the same thing but approached from a different direction by different people with different marketing terms.

One area which might be a more interesting difference to talk about might be flexibility/stability. A lot of the classic big iron work involved doing the same thing on a large scale for long periods of time whereas it seems like the modern big data crowd might be doing more ad hoc analysis, but I'm not sure that's really enough different to warrant a new term.