Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
The early scholars of the Ba `Alawi Way are often known as ‘Imam.’ Then they became to be known as ‘Shaykh.’ In latter times they became known as ‘Haba’ib.’ What is the reason behind this?
This relates to the era in which they lived. When the term ‘Imam’ was widely used in the Ummah, that term was used. Then when the concept of the Shaykh of Tariqah became widespread, they used that term. They then increased in number and some of them had reached the rank of ‘Imam’ or ‘Shaykh’ and some had not, so the term ‘Habib’ was used to include all of them. The word ‘Habib’ means the one who is loved for Allah’s sake. Love for the relatives of the Prophet ﷺ is a requirement. Allah says to the Prophet: Say: I do not ask any reward from you for this (conveying the message) other than love for (my) kinsfolk.
 Al-Shura, 42:23