Personally I’ve never seen modelling ALA T-Splines, Power Surfacing for SolidWorks. CATIA, NX, etc, referred to as sculpting. I think “freeform NURBS modelling” is probably the most appropriate term that could be used for it. Or just freeform modelling or freeform surfacing or something.
That said, what do you find the benefits of SUB-D or ZBrush/Mudbox compared to T-Splines? Unless you’re doing extremely descriptive modelling of faces or something I can’t see the benefits of knowing it as a product designer. It would be easy to outsource such modelling to 3-D artists.