Salaf are those who have preceded you. But, when religious people speak this word then it means ?pious predecessors? like Companions of the Prophet (Sallallahu Alaihi Wasallah) and their followers. Sometimes, the past scholars and pious personalities are alos meant by this word.
But, there is a group who denies the explanations of the Quran and Hadith that have been narrated by the Four Imams, instead it follows its own explanation of Quran and Hadith and claims to follow Hadith. This group condemns following any Imam rather it abuses them; therefore they are called Ghair Muqallid.
On the contrary, the majority of Ummah follows the explanations of Quran and Hadith according to Four Imams. In every age, the leading religious personalities and scholars have followed these Imams. Those who follow the Four Imams are called Hanafi, Shafei, Maliki and Hanbali.
The larger majority of Indian Muslims follows Imam Abu Hanifa and holds the belief of Ahl-e-Sunnah wa-Jamaat. The Ulama of Deoband and their followers are distinguished among them in following sunnah and abstaining from bidah (innovation); therefore they are called Deobandi. They follow Imam Abu Hanifa and hold the beliefs of Ahl-e-Sunnah wal-Jamaat and associate themselves to Hazrat Shah Waliullah and his pupils and their disciples like Hazrat Maulana Rashid Ahmad Gangohi and Hazrat Maulana Qasim Nanotawi.
In order to know the ideology of Salafiat, please study Salafiat: Aik Jaizah, written by Ramzan al-Buti, translated by Maulana Muhammad Arif, Teacher Darul Uloom, Deoband, published by Markaz-e-Dawat-o-Tahqeeq, Deoband.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband