In general, the "role" of a party on a construction project can be determined by the hiring party. Parties hired directly by the property owner are, therefore, direct contractors (or, in some cases, perhaps "handymen").
It makes sense that notice requirements are generally dependent on who the hiring party was rather than some other potential classification, because of the purpose notices are supposed to fulfill. A party can be a "direct contractor" without being someone who a "general contractor" in name or deed. Since the property owner already knows that this person is on the project (since s/he was the hiring party) there is no specific need to provide an additional notice to the owner of that fact.