In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
The reward for praying at any spot within the boundaries of Al-Aqsa Mosque, at its yards and under its trees, is the same as praying inside the Mosque itself.
Answering your question, the General Iftaa’ Department in Jordan, states the following:
As a privilege granted by Almighty Allah, Al-Aqsa Mosque is one of the three mosques in which the reward of prayer is multiplied.
This is supported by the hadith where the Prophet (peace be upon him) said, “One prayer at Al-Masjid Al-Haram is better than a hundred thousand prayers in any other mosque, a thousand prayers at my mosque and five hundred prayers at Al-Aqsa Mosque.” (Al-Baihaqi)
Al-Aqsa is estimated at 144 dunums including the Dome of the Rock, the Masjid al-Qibli in addition to about two hundred other sites.
The Dome of the Rock is the highest point at Al-Aqsa Mosque and is located in a central position.
In fact, Al-Aqsa Mosque refers to every site located within its walls. This includes all its yards, domes, the Dome of the Rock`s Mosque, Al-Buraq wall in addition to sites beneath the Mosque and above it.
Judge Mujir al-Deen al-Hanbali defined Al-Aqsa Mosque and outlined its various sites where he said, “Al-Aqsa Mosque is every site located within its walls.” (Al-Uns Al-Jaleel fi Tarikh Al-Quds wa Al-Khaleel)
Moreover, the Noble Quran named it Al-Aqsa Mosque (The Farthest Mosque) as reflected in the following verse, “Glory be to Him Who carried His servant by night from the Sacred Mosque to the Farthest Mosque; the environs of which We have blessed, that We might show him some of Our signs. Indeed He is the Hearing, the Seeing.” (Al-Israa 17:1)
In conclusion, the reward for praying at any spot within the boundaries of Al-Aqsa Mosque, at its yards and under its trees, is the same as praying inside the Mosque itself.
Almighty Allah knows best.