Is there any way to tell the difference between concussion and a coma?

Yes: A concussion is a traumatic injury to the brain that typically results from a blow to the head, and may or may not result in the loss of consciousness. A coma, on the other hand, is a state of unconsciousness in which people do not interact with the environment. The causes and outcomes of coma vary.

Yes: People in a coma are non responsive to most stimuli. They may appear to be asleep. Those with a concussion can be responsive, conversant but unaware of specifics as to time, place or person. They may have visual distortions, lapses in memory, or disorientation, to name a few of the possible symptoms.