1. diffusion is a physical process when there is random motion of molecules by which there is a net flow of matter from a region of high concentration to a region of low concentration.
2. Osmosis is the diffusion of water where molecules of water move passively (without energy) from high concentration to low concentration. eg: the way water rushes into a sponge.
3. Active transport moves particles from low to higher concentration. The difference between diffusion and active transport is diffusion does not require energy (eg: oxygen moving from the airways to the lungs - there is very little oxygen in the lungs but lots in the air). whereas active transport does require energy (eg: when plants take up nutrients from the soil. The soil does not have a large concentration of nutrients, but the plant does)
