So my understanding at least, is that any type of training where you top the plant and build a hub, is Manifolding. Mainlining is just one form of Manifolding, where you build a manifold off of the same node.
Manifolding could be done with more than one node, such as using both the second and third nodes for instance, but to be actual mainlining, your manifold has to be built off of just one node, so that each Cola receives equal energy from the plant.