Main lake would usually be the most open body of water on the lake. If you look at lake fork for example, there are 2 arms/forks of the lake that come together down at the dam. Those two arms would be considered the main lake to me, and the points extended out into those arms would be the main lake points. One you go back into coves etc I would say you are no longer on the main lake. Secondary points would be the first points inside the main coves/areas after the main lake points. I may not have gotten all that right but that is my understanding, maybe one of the more seasoned members can do a little better job of describing it. Welcome to the Forum and to Bass fishing, its addictive.