Diffusion is the movement of particles (gases and liquids) from an area of high concentration to an area of low concentration. No energy is required (it is a passive process).Osmosis is the movement of water from an area of high water concentration to an area of low water concentration, via a semi-permeable membrane (a membrane which has holes small enough to let water through in cells).Active transport is the movement of mineral ions from an area of low concentration to an area of high concentration. Energy is required (it is an active process).