The difference between Ihtiyat Mustahab & Ihtiyat Wajib

Ihtiyat Mustahab always accompanies a Fatwa, meaning, in that ruling, and the Muqallid can act either according to the Fatwa or the Ihtiyat, whichever one he prefers to act upon. For example, in this ruling:

Washing a Najis dish in Kurr Water once makes the dish Tahir, although the Ihtiyat is that it should be washed three times.

Ihtiyat Wajib does not accompany a Fatwa, and therefore, the Muqallid must act according to the Ihtiyat, but he is also able to refer this rule to another Mujtahid (perform Ruju') – for example:

The Ihtiyat is that one does not perform Sajdah on the leaf of the grape tree if it is a fresh leaf.