When Prophet Haroon (AS) was alive, he was the deputy of Prophet Musa (AS), and was the partner of Musa in his responsibility and real helper and supporter of Musa, but he passed away during the life of Musa (AS). Had he lived after the passing away of Musa, no one was entitled to succeed Musa but Haroon.
The status of Haroon from Musa is similar to the status of Ali (AS) from Muhammad (SAWA). (Saheeh al-Bukhari; Hadeeth numbers 3430 and 4064.) and Saheeh Muslim; Hadeeth numbers 4416, and 4419 and 4420 and 4421.
Thise understand Quran can obviously see the status Ali (AS) from the Prophet (SAWA) which is superior to all Muslim Ummah.