One big difference between osmosis and diffusion is that both solvent and solute particles are free to move in diffusion, but when we talk about osmosis, only the solvent molecules (water molecules) cross the membrane. read more
The main difference between diffusion and active transport is that diffusion is a passive transport method in which molecules move across the cell membrane through a concentration gradient whereas active transport requires cellular energy in order to transport molecules against the concentration gradient. read more
3)Facilitated diffusion is a type of passive transport in which ions/molecules cross the semi permeable membrane because permeases present in the membrane facilitate the transport. Like simple diffusion facilitated diffusion doesn't require metabolic energy and simply occurs across the concentration gradient. read more