(a) Diffusion and osmosis: Diffusion is the movement of molecules from a region of their high concentration to a region of low concentration. The particles can be gas or liquid. Whereas osmosis includes the movement of solvent from a solution of low concentration to a solution of a high concentration of solute across a semi-permeable membrane.
(b) Transpiration and Evaporation : Evaporation is the simple process of conversion of liquid water into water vapours whereas Transpiration is the process of release of water vapours from the stomata of plants
(c) Osmotic potential and osmotic pressure: Osmotic potential is the measure of water potential for its movement through a region of low solute concentration to a region of high solute concentration. Whereas osmotic pressure is the equivalent pressure that would be applied to a solution to prevent the flow of water across the semi-permeable membrane.
(d) Imbibition and diffusion: Imbibition is a special phenomenon in which water is absorbed by solid (colloids) in large amounts causing a huge change in their volume whereas diffusion is a simple process of movement of particles from a region of their high concentration to a region of their low concentration.
(e) Apoplast and symplast pathways : Apoplastic movement is the movement of water when it cannot enter the protoplasm and just passed through the cell walls of neighbouring cells and the intercellular spaces whereas the symplastic pathway is the movement of water from a continuous region of cells connected by their protoplasts and here water can enter the protoplasm of the cells.
(f) Guttation is the process of releasing small water droplets from the pores of the plants known as hydathodes whereas the process of Transpiration involves the release of water vapour from the stomata of the plants into the atmosphere.