Answer:
Invented in 1798 by Alois Senefelder, lithography uses the fact that oil and water don't mix as the basis of the printing process. A flat stone such as limestone or a metal plate is treated so that the image area attracts oil-based inks and the wet non-image areas repel the oil-based inks.
In this Defacto Advertisement for Nicotine Addiction the emphasis is being placed on the cigarette wrapped around the woman's neck and strangling her. The designer chose to make this stand out in order to draw attention to it. Most of the colors are muted and gray while the cigarette is white which sticks out against the dull background. Perhaps the designer wanted to point out that in the decision to smoke the woman is strangling herself and cutting her life short.
In the second advertisement for Let Go most of the attention is drawn towards the woman standing as if she was holding a DSLR camera but her hands are empty. Our eyes are drawn to this image and we begin to wonder why she is not holding a camera, but looking down we see the camera has been sold on Let Go. The designer put emphasis on the woman to show how that even before she finished taking the picture her camera was already sold on Let Go. Implying the speed of their service.