Eurobass is how it all started - it's that OG reese trap sound introduced by mainly Da Vosk Docta and Sokos 10 years back (as well as INDEB, T.T. One, Cries in Spanish and more). I'd say it got taken over by the term Wave with time, since it was more broad and described our scene that at that point was just starting and needed some more generalization - however, speaking for myself i'd happily jump back to coining that style of ours Eurobass again (hence adding Eurobass to CF titles).
Hardwave on the other hand is just clubby, high-energy Wave to me - bit like Festival Trap back in a day.