Difference between Umrah and Hajj
Sheikh Ahmad Kutty amswered this using three points:
1) Hajj is the fifth pillar of Islam, and it is mandatory for everyone who is physically and financially able to perform it once in a lifetime. `Umrah is not a pillar of Islam and it is only recommended and not obligatory.
2) Hajj must be performed in the prescribed time period, namely the months of Hajj, and even more specifically, the major rites are done in the first two weeks of Dhul- Hijjah. `Umrah, however, can be done any time of the year.
3) 'Umrah involves only the rites of Tawaf and Sa`i with ihram; whereas Hajj involves staying in Mina, performing the rite of wuquf (standing) in the plains of `Arafat, staying in Muzdalifah, and pelting the stone pillars, as well as sacrifice in some cases. `Umrah, however, does not involve any of these.