The concept of sudden cardiac death exists, but there doesn't seem to be an equivalent term for "sudden brain death." For instance, if a large cerebral hemorrhage occurs and the patient dies within a very short time, this is referred to as death due to cerebral hemorrhage, not sudden death. Sudden death is characterized by death occurring unexpectedly within just a few minutes. The main difference between these, I think, is time. Sudden cardiac death happens very quickly and unexpectedly, which is why it's termed sudden death. In the case of brain-related issues, such as a significant cerebral hemorrhage, especially in the brainstem, it can compress the vital centers, leading to rapid respiratory and circulatory failure, and eventually death. Compared to sudden cardiac death, there is a slight delay in brain-related deaths; they don't occur as swiftly, and I believe the major difference lies in the timing.