Diffusion

Osmosis

1.It is the process of movement of the molecules from high concentration to low concentration until molecules get uniformly distributed.

1.It is the process of diffusion of only solvent of water molecules from its higher concentration to lower concentration via semi permeable membrane.

2. Semi permeable membrane is not needed.

2. Semi permeable membrane is essential. 

3. It involves the movement of both solute and solvent

3. Osmosis involves movement of solvent molecules only.