What is the difference between Hijri calendar?

The Islamic calendar, also known as the Muslim calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. Being a purely lunar calendar, it is not synchronized with the seasons. With an annual drift of 10 or 11 days, the seasonal relation repeats about every 33 Islamic years.

It is used to date events in many Muslim countries (concurrently with the Gregorian calendar), and used by Muslims everywhere to determine the proper days on which to fast Ramadan and perform Hajj, in addition to celebrate other Islamic holy days and festivals.

The first year was the Islamic year beginning in 622 CE during which the emigration of the Islamic prophet Muhammad from Mecca to Medina, known as the Hijra, occurred. Each numbered year is designated either H for Hijra or AH for the Latin anno Hegirae (in the year of the Hijra).[1]

The current Islamic year is 1433 AH, from approximately 26 November 2011 (evening) to 14 November 2012 (evening).

It is also called the Hijri calendar, (Arabic: التقويم الهجري‎; at-taqwīm al-hijrī; Persian: تقویم هجری قمری ‎ taqvim-e hejri-ye qamari; Turkish: Hicri Takvim; Urdu: اسلامی تقویم Islami taqwīm; Indonesian: Kalender Hijriah; Malay: Takwim Hijrah)