Don't know nowt about prog-house but I agree that Prodigy were hardcore but I'd also say that these terms are sub-categories of electronic music as a whole..
..so for the majority of people who don't know terms like prog/electro/jackin etc, those artists would be electronic music which to me would mean techno..
..I think that with some electronic music, it's only with experience and the benefit of a bit of time that you can categorise them in those sorts of genres..when they first come out they are either so revolutionary or different that only after a few subsequent similiar releases can they be categorised and given their own sub-category..I'd guess that the first tune to use a 303 I'd guess wasn't instantly labelled "acid"..likewise the first breakbeat tunes that started to come out weren't labelled breakbeat..they were just labelled "techno"releases..#
..maybe
But tekno to me is just a sub-category of techno..I've only really noticed it being used in the past few years anyway..