All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Linguistically, Hajj means repairing to a place for the sake of visit of something glorified, and in Islamic terminology, it implies the repairing to the House of Allah to observe the necessary devotions as Ihram, standing at Mount ‘Arafah and performing Sa'y in a specified time (Shawwal, Thul-Qi'dah and Thul-Hijjah).
‘Umrah literally means a visit, and in Islamic terminology, it means a visit to the House of Allah at any time of the year without standing at Mount ‘Arafah; i.e., it consists of Tawaaf around the Ka'bah, Sa'y between As-Safa and Al-Marwah in the state of Ihram.
Other actions, such as throwing the pebbles and staying at Mina, are only related to Hajj.
Allah knows best.