passive transport is transport or movement of substances along concentration gradient.
Facilitated transport unlike passive transport uses specialised carrier proteins [they are specific for a substance} for transport along concentration gradient.
For facilitated transport to take place no ATP is required.
But a concentration gradient is required
Active transport requires ATP for transport of substance and tansports against the concentration gradient.
If the particles can only pass through protein channels, then the rate of diffusion is determined by the number of channels as well as the number of particles
Both facilitated and active transport transport saturates.
Saturation which leads to a decrease in transport across the membrane as there are a limited number of carriers which might be fully active.