Why is Abu Ja'far Yazid ibn al-Qa'qa' not given the title of "Qari'," while Nafi' is given the title of "Rawi?"

Imam Nafi' was the leading reciter (Imam of Qira'a) in Medina. He learned recitation from seventy of the Tabi'in (successors), among whom were: Abd al-Rahman ibn Hurmuz al-A'raj, Abu Ja'far Yazid ibn al-Qa'qa', Shaybah ibn Nisah, Muslim ibn Jundub al-Hudhali, and Abu Ruh Yazid ibn Ruman. Nafi' taught people recitation for over seventy years, and the recitation of the people of Medina became attributed to him. Malik, al-Layth ibn Sa'd, and others said: "Indeed, Nafi''s recitation is a Sunnah."