text: what is the difference between the two brand (bayer &federated pharmaceutical) which makes asprin? i need the diffence in concentration if any one is stronger and what is the chemical build up of these asprin (i need answer a.s.a.p lab crisis) well, the concentration is probably different for each, but it would simply be the milligrams of acetylsalycilic acid in each tabled over the number of milligrams the actual pill weighs.   the chemical makeup will be the same - aspirin is aspirin. however, some add different ingredients to make it easier on the stomach, or to go down easier or to be absorbed quicker. look at the bottle or box they came it - it will tell you what is in each.