Muslims don't learn to pray by reading hadith, they learn from their parents, who learned from their parents, who learned from their parents, and so on, and so on. These day to day practices (in my opinion) would be difficult to fabricate or insert in to the religion. So to me that would be following the Sunna.

The hadith then expound on the sunna, which I think is what the original post is trying to say. Because they are transmitted orally and not physical day to day actions it is easier for fabrications to slip in. I am not trying to say all hadiths are fabrications, that is not what I personally believe. But we do know from the fact the Bukhari rejected so many that there were people who were fabricating hadith and attributing them to the prophet.