What is the difference between hijrah and the hajj?

Hijrah refers to the migration of Prophet Muhammad and his followers from Mecca to Medina in 622 CE. It is considered a significant event in Islamic history. Hajj, on the other hand, is the pilgrimage to Mecca that Muslims are required to undertake at least once in their lifetime if they are physically and financially able. It is one of the Five Pillars of Islam.