Yes, bifocals have 2 lenses, one for reading and one for distance; they are cemented together to form one lens. Varifocals have one lens which gradually changes the focal length as you get to the bottom of the lens. Thus, keeping your head still, as you look downwards to read you look through the correct part of the lens for the print to be clear. It has the advantage that middle-distance objects are in focus, as you look through the correct part of the lens for that too. A further advantage is that there is no obvious "reading" part of the lens, so they are aesthetically better (if you care).