osmolarity is a reference to 'osmotic pressure', and the concentration of a solute in solution. The most accurate way to talk about dissolved solids is Molarity (M). A mole is 6.02 x 10^23 atoms.
Osmolarity is a means of measurement conducted in osmomoles per liter of solution. The osmole is the number of moles of a substance such as a solution that contributes to the osmotic pressure of the solution.
