Osmosis

Osmosis is the movement of solvent molecules from a dilute solution to a concentrated solution across a semi-permeable membrane.

Osmosis unlike diffusion is a movement from low concentration to high concentration. It also involves two solutions of different concentration. These two solutions will be separated by a semi-permeable membrane.

The solution in A will move to solution B. The solution in A is lowly concentrated (water) and the solution in B is highly concentrated (salt or sugar solution) The solution in A which is water can also be referred to as high concentration of water molecules. The solution in B can also be referred to as low concentration of water molecules.