As a medical professional with expertise in neurology, I can explain the differences between a coma and brain death. A coma is a state of unconsciousness where a person cannot be awakened and is unresponsive to stimuli. However, in a coma, the person still has brain stem function, which means they can continue to breathe on their own, their heart can beat, and they may have reflexes. The brain may still show some activity, and there is a possibility, however small, that the person could recover some level of consciousness. On the other hand, brain death is the irreversible end of all functions of the brain, including the brain stem. When someone is declared brain dead, they are legally and clinically dead. There is no breathing, no circulation, and no possibility of recovery because the brain and brain stem have ceased all activity. In summary, the key difference lies in the level of brain function. In a coma, there is some preservation of brain stem function, whereas in brain death, there is a complete and irreversible loss of all brain functions. read more >>

Brain death: These patients are no longer alive. There has been an irreversible cessation of all activity in both the brain and the brain stem. ... Coma is distinguished from brain death by the presence of brain stem responses, spontaneous breathing or non-purposeful motor responses.read more >>