1 molar aqueous solution is more concentrated than 1 molar aqueous solution because 1 molar solution contain 1 mole of solute in 1 litre of the solution which include both solute and solvent. So, the mass of solvent (i.e. water) is less than 1000 gram. Therefore 1 molar aqueous solution contains 1 mole of solute in less than 1000 gram of solvent whereas 1 molar solution has 1 mole of solute in 1000 gram of solvent. Hence concentration will be more in 1 molar aqueous solution.