Diffusion is the movement of a molecule from an area where the molecule is in high concentration to an area where the molecule is in low concentration. Facilitated diffusion is the movement of a molecule from an area of high concentration to an area where the molecule is in low concentration. Osmosis is the diffusion (high to low concentration) of water through a semi-permeable membrane. Water moves from an area of high water molecule concentration (and lower solute concentration) to an area of low concentration (and higher solute concentration.
