Visually, hulled barley is tan and elongated; pearled barley is sort of pearly and rounded.

Hulled barley is also known as barley groats, only the outer hull is removed. pearl barley has the out husk and the bran layer removed. You can substitute one for the other, but adjust the cooking time as barley groats can take more than an hour to cook, while pearl barley takes about 40 minutes.