A laqab is an additional designation by which a person becomes known. It may refer to a physical characteristic, a habit or some other recognized attribute. Names, kunyahs and titles all identify persons, but they are not the same form of designation.
Ism: a personal name, such as Sulaymān.
Kunya: usually a designation beginning with Abū or Umm.
Laqab: a recognized descriptive title, such as al-Aʿmash or al-Aʿraj.
A title appearing in a chain does not by itself create another transmitter. To establish that a name and a title refer to one person, compare teachers, pupils and chronological evidence.