What is the difference between osmosis and diffusion? a. diffusion is the movement of molecules from an area of low concentration to an area of low concentration. osmosis is the opposite. b. osmosis the movement of molecules from an area of low concentration to an area of low concentration. diffusion is the opposite. c. osmosis is the movement of water across the membrane; diffusion is the movement of molecules from a higher to a lower concentration. with or without the presence of a membrane. d. diffusion is the movement of water across the membrane; osmosis is the movement of molecules from a higher to a lower concentration. with or without the presence of a membrane. answer asap!