A muʿjizah specifically confirms the prophetic claim. A karāmah may occur for a saintly believer but does not make that person a bearer of revelation or a new religious law. Irhāṣ designates an extraordinary precursor before the announcement of a prophetic mission.
An externally similar event can be classified differently when its context changes. An event before a later prophet's mission does not automatically possess all the conditions of a challenge-miracle.
Establishing the possibility of saintly favors and establishing the truth of a claimed prophethood are separate theological questions.