There are three types of pilgrimages:
The first is the obligation on those who reside more than 48 miles from Makkah and the other two are prescribed for those who reside within 48 miles of Makkah.
This is divided into two parts.
The first part of pilgrimage is Umra-ut-Tamattu the reason might be that during the Umra the cleansing of soul begins and during the pilgrimage rites it reaches its zenith. A person's soul heats up during Umra and pilgrimage cooks it completely. A hot thing can become cold but a cooked thing cannot become raw.
If while performing Umra the body made the soul do tawaf then during the pilgrimage the soul should guide the body during tawaf.