Pediatrics is the study of growth and development of the child  from the genetic background and moment of conception through adolescence.
 
 It is the science and art of prevention, diagnosis, and treatment of the diseases of children from birth through adolescence.....

Disparity in occurrence and progression  of disease between children and adult

congenital anomalies        inborn errors of             
            metabolism    more common in children   
   newborn,  infants  vulnerable to infection
   sinusitis rare in infancy
   infants vulnerable to obstruction in respiratory 
            tract......