Describe the process of facilitated diffusion. How does it differ from simple diffusion?

Facilitated diffusion is a type of passive transport where molecules move across a cell membrane down their concentration gradient with the help of specific transport proteins (channel proteins or carrier proteins). It differs from simple diffusion because it requires these protein helpers, which allow larger or charged molecules (that cannot easily pass through the lipid bilayer) to cross the membrane. Both simple and facilitated diffusion do not require cellular energy (ATP).