What is the difference between ittifaq (agreement) and ijma' (consensus) in Fiqh, 'Aqidah, and 'Ilm al-Kalam from the perspective of doctrine?

Linguistically, Ijma' (consensus) is defined as determination and agreement. Technically, it is the agreement of the scholars of an era from the Ummah of Muhammad, peace and blessings be upon him, on a matter of religion.

The term ittifaq (agreement) is sometimes used for ijma', and sometimes for something more specific, such as the agreement of the four Imams, or the people of a particular madhhab (school of thought), or what is lacking a condition of ijma'.

Every ijma' is an ittifaq, but not every ittifaq is an ijma'. For instance, differing parties may agree after a long period, but this is not considered ijma'. Also, ittifaq may refer to the agreement of the people of a single madhhab, whereas ijma' encompasses the agreement of all Islamic scholars.

Among the differences between them are: 1. Ittifaq may refer to the agreement of the four Imams. 2. Sometimes ittifaq refers to the agreement of the people of a madhhab. 3. Ittifaq can be presumptive (dhanni), while ijma' is definitive (qat'i), affirmed by the scholar.