Many of us have travelled abroad and most of us would have carried Regular passport.
But there are other different types of passport that are issues by Indian government.

Regular passport (Black cover) – Issued to regular citizens for ordinary travel, such as for vacation, study and business trips (36 or 60 pages). It is a Type “P” passport – P stands for personal.

Official passport (White cover) – Issued to individuals representing the Indian government on official business. It is a Type “S” passport – S stands for Service.

Diplomatic passport (Maroon cover) – Issued to Indian diplomats, top ranking government officials and diplomatic couriers. It is a Type “D” passport – D stands for Diplomat.

Hajj passport – Issued to Indian Muslims not holding ordinary passport, for Hajj pilgrimage.

In addition, selected passport offices in India as well as overseas missions are authorised to issue Regular Indo-Bangladesh passports and Indo-Sri Lankan passports, to Indian nationals resident in West Bengal, the North Eastern States, Tamil Nadu and Pondicherry. These two passports respectively permit travel to Bangladesh and Sri Lanka only and are not valid for travel to other foreign countries.

Source: http://en.wikipedia.org/wiki/Indian_passport