What characterstics is shared by simple diffusion and facilitated diffusion?
Both involve the movement of a substance from regions of a higher concentration to lower concentration without cellular energy.
Movement of substances from a region of high to low concentration takes place till equilibrium is achieved. If the transport takes place with the help of a transporter protein embedded in the plasma membrane it is called facilitated transport, for e.g. transport of glucose. Thus, diffusion is similar to facilitated diffusion as transport of molecules takes place from region of high concentration to low concentration without the requirement of energy.