Different constraints will be generated depending on the method of geometry creation. The Parallel, Perpendicular, Horizontal, Tangent by 2 buttons in the Draw group on the Drafting tab convey different intentions, and all will result in different constraints.

Even if two drawings look identical, they probably will have different constraints if different construction techniques were used to create them. For example, consider these two lines. Each is connected to a fixed point at one end. But one was created with 2 Points and the other was created with Angle & Length. Both drawings look the same: