How can solutions be different?
By composition, and by concentration...
Clearly, we can prepare solutions of different solutes, and with DIFFERENT SOLVENTS...we are not forced to use water as a solvent, and many solutes would not be water-soluble. And of course, given some degree of solubility in the solvent, we could prepare solutions of different concentration, i.e. a different amount of solute per volume of solution...
Typically, solution concentration is reported as a