[COLOR=DarkOrchid][SIZE=3][FONT=Comic Sans MS]Fulling is done to a wool fabric. Once it's crocheted, knitted or woven and then agitated with a change in pH and water temp, it's considered a fulled object. The popular Fiber Trends Clogs are fulled, not felted.
Felting is done to the wool before it's changed into a fabric. Wool batting is laid out, dampened with water and something to change the pH (vinegar or soap works fine) and manipulated to cause the cuticle (little scales or hooks) on the wool strand to tangle with the cuticle on other wool strands. As they tangle more, they pull together causing the shrinking. Felting can also be done dry with specially barbed needles and is generally referred to as needle felting.
Boiling is yet another method of fulling. More information can be found here.
Fulling and felting are often used to mean the same thing, but are actually two different ways of creating a strong, water resistent woolen item. Like knitting and crocheting are the same in as far as they manipulate yarn into a fabric, fulling and felting manipulate wool are the same in that the end result is a thick woolen fabric achieved by two different methods.