Ndebele and Herringbone are the same stitch. The stitch originated with the Ndebele (pronounced N-da-belly) tribe in South Africa - hence the name. However, once the stitch made it's way to America people saw how the design was similar to a cloth weave called herringbone. The word herringbone was easier to pronounce than ndebele so the name stuck. In the beading world using either name is fine.