Her face lift did a better-than-average job of tightening her cervical angle.  What's the cervical angle?  Let's draw more lines.  Picture a line that ascends the skin along the front of her neck, and another line that goes backward from her chin toward the front of her neck.  The area where the underside of her chin meets the front of her neck is a fairly distinct angle in the after picture, whereas the skin makes a gentle curve from the chin to the front of the neck in the before picture.

It's usually difficult to make the cervical angle this tight during a face lift, because the cervical angle is the farthest point from where the face lift incisions are made.  But sometimes things just fall into place.  Different people will obtain different amounts of improvement in the area of the cervical angle, even if the operation is performed with technical skill every time.