Suddenly there’s bulgur wheat?

The recipe teaches how to convert wheat berries into bulgur.

Bulgur wheat used for making tabbouleh starts life as a wheat berry. The berries get parcooked or softened by soaking, dried and cracked into bits- precisely as you do in the recipe. So to answer your question, the wheat berries become bulgur wheat once they are cracked in the mill. That shortens the final cooking time considerably. They are one and the same thing. A wheat berry is simply one tiny bit from an "ear" of wheat, and besides being called a wheat berry is also called a kernal, a kern, or a corn. Or a seed, perhaps, since that's what it is, a wheat seed.

Guessing the author modified an existing recipe for tabouli that used bulgur, and now they are using wheat berries.