Well, not quite. The switching PS uses high frequency switching transistors that are not in a state or condition that passes maximum current constantly but only when called for. These are much more efficient than constant current PS's and also cost a lot less to make. No need for a huge chunk of copper. They also need to be designed to minimize RF noise created by their HF switching. If not they can wreak havoc on your other electronics. They're also sensitive to the types of loads they see. But they're definitely not variable current unless designed that way.