What is the difference between a doctor, a preacher, and a scholar in Islamic Sharia?

The title "Doctorate" is awarded academically in any field after specialized study or the authorship of a work. As for the term "Islamic preacher" (Da'i Islam), it is applied to anyone who spreads the religion of Allah through preaching or teaching, and it does not require mastery of all Shariah sciences, based on the Prophet's (peace be upon him) saying: "Convey from me, even if it is a single verse." The title "Scholar in Islamic Law" (Alim fi al-Shariah al-Islamiyah) is given to someone who possesses proficient knowledge of the sciences of Shariah and its tools, such as grammar, morphology, rhetoric, and eloquence.