Is there a difference between coma and loss of consciousness?

Continuum: Coma is the deepest form of loss of consciousness (loc), in which no responsiveness to the external environment exists. This can be reversible. Technically a concussion with loc means a momentary coma has occurred but the term is rarely used in that circumstance. Simple loc means loss of awareness to some external stimuli with preserved responsiveness to noxious stimuli.

Coma: In both situations there is loss of consciousness, however when we label a patient as being in coma, we usually imply that the loss of consciousness has been there for a considerable period of time, gnerally several hours to days or sometimes weeks.