Al-Qiran
The pilgrim enters into Ihram for Haj and Umrah at the same time at a Meeqat during the months of Haj. He or she will not come out of the state of Ihram until the Day of Sacrifice (10th Dhul Hijjah).
Alternatively, one may first enter into Ihram for Umrah and before beginning the Tawaf, he or she may make the intention for Haj. The Sa`ee can be done after the Tawaf of Umrah or be left to be done after Tawaf Al-Ifadah. The pilgrim performing this type of Haj is called a Qarin.
Hajj Al-Ifrad
The pilgrim enters into Ihram for Haj alone at a Meeqat during the months of Haj. Like the Qarin he remains in the state of Ihram until the 10th Dhul Hijjah. It is not obligatory on him to sacrifice an animal. No Umrah is required.
Hajj At-Tamattu
Many scholars consider this the best type of Haj, as it is what the Prophet (peace be upon him) urged his Companions to do. One performing this type of Haj is called a Muttamatti. This involves performing Umrah first during any of the months of Haj (Shawwal, Dhul-Qada and the first 10 days of Dhul Hijjah), removes the Ihram clothes after Umrah, and then re-assumes the Ihram state for Haj on the eighth day of Dhul Hijjah of the same year.
Note: For those who choose to do At-Tamattu or Al-Qiran, a mandatory sacrifice is required of them during the days of Eid. Those who live in Makkah are exempted from this requirement.
For more, see
Zindeen 