All wall types within the Basic Wall family have an instance property called Structural Usage, which specifies whether the wall is non-bearing or one of 3 kinds of structural wall (bearing, shear, or structural combined).
When you use the Wall tool, Revit assumes you are placing partition walls. Whichever wall type you select, the default Structural Usage value is non-bearing. When you use the Structural Wall tool, and select the same wall type, the default Structural Usage value is bearing. In either case, the value is read-only, but you can change it after the wall is placed.