Does alcohol really do more damage to the body of a child compared to an adult?
As is stated in this article by Hiller-Sturmhöfel and Swartzwelder from the National Institute on Alcohol Abuse and Alcoholism, there are ethical issues surrounding research on human subjects that preclude direct testing, however studies in model mammals and observational studies do find that "adolescence is a unique stage of brain development which is particularly sensitive to the disrupting effects of alcohol."

A research review by Tapert, Caldwell, and Burke, also finds that studies support the conclusions that alcohol use by adolescents and young adults has a negative effect on cognitive abilities.

Hope that begins to provide you with an answer to your question.