Mole fraction - The ratio of the number of moles of one component of a solution to the total number of moles all of the components in the solution.

The sum of mole fractions  of all the components of a solution is always equals to 1.

Molality-This is a property of a solution and is defined as the number of moles of solute per kilogram of solvent.

The Si unit is mol/kg.

Molality-This is defined as the number of moles of solute per litre of solution.

Hope you get it.