The key difference between active transport and facilitated diffusion is that the active transport occurs against the concentration gradient hence, utilizes energy to transport molecules across the membrane while the facilitated diffusion occurs along the concentration gradient hence, does not utilize energy to transport molecules across the membrane.
Molecules go in and out the cells using different transport mechanisms. Since the cells have a selectively permeable cell membrane, only some molecules or only selected molecules can go inside the cell and come out of the cell. Osmosis is the main mode of facilitating these movements in cells. Furthermore, there are two other mechanisms namely active transport and facilitated diffusion that helps molecules to move across the cell membrane. As the names suggest, active transport is an active process that utilizes ATP (energy) while the facilitated diffusion is a passive process that does not utilize ATP. That is because the active transport occurs against the concentration gradient while the facilitated diffusion occurs along the concentration gradient. However, both mechanisms take place via channel or carrier proteins located in the plasma membrane.
