Prophets receive Wahi, Imams too receive Wahi.
جُعِلْتُ فِدَاكَ أَخْبِرْنِي مَا الْفَرْقُ بَيْنَ الرَّسُولِ وَ النَّبِيِّ وَ الْإِمَامِ قَالَ فَكَتَبَ أَوْ قَالَ الْفَرْقُ بَيْنَ الرَّسُولِ وَ النَّبِيِّ وَ الْإِمَامِ أَنَّ الرَّسُولَ الَّذِي يُنْزَلُ عَلَيْهِ جَبْرَئِيلُ فَيَرَاهُ وَ يَسْمَعُ كَلَامَهُ وَ يُنْزَلُ عَلَيْهِ الْوَحْيُ وَ رُبَّمَا رَأَى فِي مَنَامِهِ نَحْوَ رُؤْيَا إِبْرَاهِيمَ ع وَ النَّبِيُّ رُبَّمَا سَمِعَ الْكَلَامَ وَ رُبَّمَا رَأَى الشَّخْصَ وَ لَمْ يَسْمَعْ وَ الْإِمَامُ هُوَ الَّذِي يَسْمَعُ الْكَلَامَ وَ لَا يَرَى الشَّخْصَ
Hasan b. Abbas once asked Imam al-Rida, peace be upon him, in a letter. “What is the difference between a messenger, a prophet, and an Imam?” The Imam answered as follows: “The messenger (rasul) is a person to whom Jibril descends and who both sees him and hears the words that he speaks. He is thus in communication with divine revelation (wahy), which he sometimes receives in the form of a dream, as was the case with Ibrahim, peace be upon him.The prophet (nabiyy) sometimes hears the words spoken by Jibril and at other times sees him without hearing anything from him. The Imam hears the words that Jibril utters without seeing him.” (al-Kulayni, al-Kafi, Vol. I, p.176, hadeeth # 2)