This can cause complete cessation of brain function. Extensive testing is performed before the confirmation of brain death is made. There is no possibility of recovery from brain death. The heart continues to beat only due to mechanical ventilation. In a coma state, the brain continues to function though it may be in varying states.
Recovery is dependent upon how much damage the brain has incurred.
This is very different from brain death. After organ recovery, they are cooled and are placed in preservatives for times that vary depending upon the organ. There are laws that allow for organ recovery without family consent if the potential donor has a signed donor card or permission noted on their driver's license. In practice, however, this is not done. Donation is always discussed with the family.