Question: Is there a difference between 'Aqeedah and Manhaj?
Answer: Manhaj is broader than 'Aqeedah. Manhaj is within 'Aqeedah, as well as in behavior, character, dealings, and in general life of the Muslim. Every course of action upon which the Muslim traverses, then it is called Manhaj. In reference to 'Aqeedah, it is understood as the fundamentals of faith, and the meaning of the two testimonies of faith (Ash-Shahaadataan), and whatever they dictate. This is 'Aqeedah.
Source: Al-Ajwibatul-Mufeedah 'an As'ilatil-Manaahij il-Jadeedah, pg. 75, question no. 35.