It might seem like a silly distinction, but Disco-House was synonymous with filter-house in my mind. Lots of disco samples (with strings) and filtered like crazy.
This playlist seems to capture well:
I never really knew the nu-disco stuff, but the little I have heard labeled that seemed to me to be more like italo-disco or boogie something or other. More lasers and linn-drums and so on.
Basically indy-dance (which was something else I never really knew about) comes to mind just to confuse things further.