Hulled barley is a whole grain barley. Pearled barley is not a whole grain

Hulled barley is the true whole grain. 

Pearled barley, however, which loses both its outer layer and its bran layer, retains most of its whole-grain nutrients and fiber.

Info source:

http://preventcancer.aicr.org/site/PageServer?pagename=elements_whole_grains%20

Pearled barley vs Hulled Barley, ( Barley hulled vs. Pearl Barley )

Info and picture source:

http://thedelicioustruth.blogspot.sg/2011/12/pearled-barley-vs-hulled-barley-whole.html?m=1

Simply put, hulled barley (right in photo) is a whole grain, meaning the three parts of the seed—bran, germ and endosperm—are intact, providing optimum nutrition. Hulled barley, as its name suggests, has had its inedible, outermost layer—the hull—removed. (All grains grown for human consumption must have their hull removed, if they have one.) 

Pearled barley (left in photo) is not a whole grain, since it has been polished (aka "pearled"), processing that removes the nutritious bran layer, making it an incomplete food. 

This concept of whole vs. incomplete holds for other grains and grain products. White rice, for example, is rice that has had its bran and germ—and with them essential vitamins, minerals, enzymes, fats, proteins and fiber—removed.