Difference between Mu’jiza and Karaamat
Mu’jiza is the miracle, which is wrought at the hands of a Prophet and Karaamat is the miracle, which is expressed through the saints.
If any apparent miracle is expressed through a non-Muslim and irreligious person, then it is called "Istidraaj." As mentioned in Sharh Aqaaid Nasafi, Pg. No. 144.