To act upon does not mean to act on cancelled hadith. If one hadith is cancelled then not to act on that will be acting on hadith which cancells that. So Whatever prophet (pbuh) ordered, to act upon that is acting upon on hadith. If prophet cancelled one hadith, then not acting on that will be obey the porphet(pbuh) again thus obey the latest hadith. So ahle hadith is supposed to act on authenticated hadiths.
Hadith which are cancelled are clear in hadith book. So to be a proper ahle-hadith one is to acting on authenticated hadith and leave cancelled one. This is what prophet (pbuh) wnats from us. He does not want us to act on cancelled hadith. So if you follow him i.e his sunnah, and that is in fact from hadith (you dont get sunnah in dreams).
The difference is not that one is acting according to sunnah and one is acting accoring to hadith because both are same. Real difference is that a common sunni will not act on hadith if it is against his imam way. So for a sunni who are muqalad too preferences go to imam and not the hadith.