Describe how the graph of y=|x|-4 is like the graph of y=|x| and how it is different.

The graph y=|x|-4 is obtained from the graph y=|x| dy moving down 4 units the graph y=|x| along the y-axis (see, if x=0, then for y=|x|, y=0 and for y=|x|-4, y=-4).
These two graphs have the same form.